Can Patron Saints be “dethroned”?
The saints who are canonized cannot be dethroned as recognizing and proclaiming a saint is an infallible act of the Church united to the Supreme Pontiff.
Let's look at the Church history in proclaiming a saint;
In the first five centuries of the Church, the process for recognizing a saint was based on public acclaim or the vox populi, vox Dei (voice of the people, voice of God). There was no formal canonical process as understood by today's standards. Beginning in the sixth century and continuing into the twelfth century, the intervention of the local bishop was required before someone could be canonized. The intervention of the local bishop usually began with a request from the local community for the bishop to recognize someone a saint. Upon studying the request and a written biography, if he found it favorable, the bishop would typically issue a decree, legitimatize the liturgical cult and thereby canonize the person.
Starting in the tenth century, a cause proceeded with the usual steps, i.e. the person's reputation would spread, a request to the local bishop from the people to declare the person a saint occurred, and a biography would be written for the bishop's review. Now however, the bishop would collect eyewitness testimony of those who knew the person and who had witnessed miracles, and he would provide a summary of the case to the Pope for his approval. The Pope then reviewed the cause, and if he approved it, he issued a decree declaring the person a canonized saint. The first documented case of papal invention is by Pope John XV on January 31, 993 for the canonization of St. Ulric. When Pope Sixtus V reorganized the Roman Curia in 1588 he established the Congregation for Sacred Rites. One of its functions was to assist the Pope with reviewing causes. Except for a few canonical developments, from 1588 the process of canonization remained the same until 1917 when a universal Code of Canon Law was promulgated.
The 1917 code contained 145 canons (cc. 1999- 2144) on causes of canonization, and mandated that an episcopal process and an apostolic process be conducted. The episcopal process consisted of the local bishop verifying the reputation of the person, ensuring that a biography existed, collecting eye witness testimony and the person's written works. All of this was then forwarded to the Congregation for Sacred Rites. The apostolic process consisted of reviewing the evidence submitted, collecting more evidence, studying the cause, investigating any alleged miracles and ultimately forwarding the cause to the Pope for his approval. This process remained in effect until 1983 with the promulgation of the 1983 Code of Canon Law and new norms for causes of canonization: Divinus Perfectionis Magister, Normae Servandae in Inquisitionibus ab Episcopis Faciendis in Causis Sanctorum and Sanctorum Mater (2007). This revised process for causes of canonization is still in force and is detailed below.
No precise count exists of those who have been proclaimed saints since the first centuries. However, in 1988, to mark its 4th centenary, the Congregation for the Causes of Saints published the first "Index ac Status Causarum." This book and its subsequent supplements, written entirely in Latin, are considered the definitive index of all causes that have been presented to the Congregation since its institution.
- Saints (USCCB)
For instance lets say there's a patron saint of infants, but that a recently canonized saint is clearly superior to the previous one when it comes to infants.
The simple answer is the Church does not make a saint but serve only as God instrument to proclaim and recognized who are the saints in God's eyes. The holiness of the saints can only be known to God as human has no faculties to determined who is much holier.The saints works in Communion with the Church and not thru competition.
Is it not then warrented to make the previous saint step down to leave the place of patron saint to someone who is holier?
Considering the lengthy process of the Church now employ in Canonizing the Saints, it would not be prudent for the Church to declare a Saint much holier as what if another Saint was discovered whose story is much more heroic, it would put the Church in a not good situation. Rather than entertaining the thoughts of a saint stepping down in favor of more a holier saint according to man's finite understanding. The faithful can invoke all the saints intercessions but the problem is one could not foster a strong devotion to a particular saint.
Other issues like St. Philomena's case and other saints not yet fully canonized;
The USCCB has the following introduction with regards to recognized Saint not officially canonized.
All Christians are called to be saints. Saints are persons in heaven (officially canonized or not), who lived vitreous lives in a heroic way or were martyred for the faith, and who are worthy of imitation.
In official Church procedures there are three steps to sainthood: a candidate becomes "Venerable," then "Blessed" and then "Saint." Venerable is the title given to a deceased person recognized formally by the pope as having lived a heroically virtuous life. To be beatified and recognized as a Blessed, one miracle acquired through the candidate's intercession is required in addition to recognition of heroic virtue. Canonization requires a second miracle after beatification. The pope may waive these requirements. A miracle is not required prior to a martyr's beatification, but one is required before canonization. - Saints (USCCB)
Let's take a look at St.Philomena's case as the USCCB declared that "Saints are persons in heaven (officially canonized or not)".
St. Philomena was liturgically canonized on January 13,1837 as a local saint in Mugnano, Italy and Pope Gregory XVI allowed the public cultus of St. Philomena but officially does not solemnly canonized her, Why?
Pope Gregory XVI, on January 13, 1837, in a solemn decree based solely on power of her undeniable miracles, raised an unknown thirteen-year-old early martyr named Philomena to the altar of the Church, granting a Mass in her honor, and thereby giving official approval to public devotion to her. This liturgical honor constituted the only instance of a Proper office being granted to a saint from the catacombs of whom nothing is known except her name and the bare fact that she was martyred for the Faith. “Filumena” was now officially St. Philomena, a canonized saint of the Catholic Church. - It is Time to Meet St. Philomena
This is the wise judgment or prudence that Pope Gregory XVI had taken as he allowed St. Philomena veneration to stood the test of time and give the future Popes to take the necessary step if St. Philomena is worthy to become not just a local Saint but be recognize also as a Universal Saint.
The actions thru Magisterial decrees of the succeeding Popes elevated the glorious saint and wonder worker St.Philomena cult to Confraternity to Universal Archconfraternity.
The Popes of the Nineteenth and Twentieth Centuries
The Holy Fathers of the nineteenth and early twentieth century manifested remarkable devotion to the young Princess Virgin-Martyr. For example:
Pope Leo XII granted permission for altars to be dedicated and chapels to be erected in her honor, calling her the “Great Saint”. Pope Gregory XVI called St. Philomena the “Thaumaturga,” the “wonder-worker” of the nineteenth century, and, as already mentioned, in 1837 he raised her to the “altar of the Church” with public devotion. He granted her a special feast (August 11) and also approved a Mass in her honor.
Blessed Pope Pius IX had an exemplary devotion to St. Philomena. While still a bishop, he went on pilgrimage several times to her tomb to offer Mass, and as Pope, he declared St. Philomena the “Patroness of the Children of Mary”.
Pope Leo XIII was another pope in the list of pontiffs who had a special love for St. Philomena. He also had a strong devotion to her before becoming Vicar of Christ. It was Leo XIII who commissioned the beginning of the Archconfraternity of St. Philomena, and it was he who with an almost unprecedented generosity approved and granted an indulgence to the wearing of the “Cord of St. Philomena”. This cord, which we will discuss in more detail later, was colored white and red in honor of the virginity and martyrdom of St. Philomena, and was strongly promoted by St. John Vianney (to whom most historians attribute the origins of the Cord). Not only did Leo XIII grant a plenary indulgence for those who wore the cord for the first time, but he also granted a plenary indulgence for three liturgical times of the year associated with St. Philomena. Furthermore, a plenary indulgence was granted to those wearing of the Cord at the hour of their death.
In the twentieth century, Pope St. Pius X continued the strong papal tradition of veneration of St. Philomena. In 1905, on the occasion of the centenary of her arrival in Mugnano, he sent his gold ring to adorn the image of St. Philomena located over her tomb. In that same year, he beatified the Curé of Ars, St. John Vianney, who had such a primordial devotion to St. Philomena.
St. Pius X was also a great advocate of wearing the Cord of St. Philomena and
declared, “all the decisions and declarations of his predecessors regarding St. Philomena should in no way be altered”. With this act he perpetuated devotion to St. Philomena for all times. Pius X also elevated the archconfraternity of St. Philomena to the status of a universal archconfraternity.
In sum, nineteen acts of the Holy See during the pontificates of five popes were issued in positive promotion of popular devotion to St. Philomena, in the forms of public liturgical veneration, archconfraternities, and plenary and partial indulgences. This succession of papal veneration and indulgences is arguably unprecedented in the pontifical granting of devotional privileges for any modern saint.
From the year 1837 to 1961 St. Philomena cult was venerated not just from Italy but it spreads all over the Universal Church.
St. Philomena was recognized and venerated as a local Saint in 1837 and wonderfully rise up to be recognized universally as a Saint.If we count the number of years of St.Philomena veneration before the Congregation of Rites issued a "liturgical directives" to remove her name in the liturgical calendar in 1961, it was already over 100 years that St.Philomena was venerated by the Catholic Church universally.
This is the wisdom of Pope Gregory XVI as he did not undermine the instruction and prohibition issued by Pope Urban VIII's Cælestis Hierusalem Cives not to immediately proclaim any saint by solemnly canonizing without the prescribed period of 100 years proven veneration. St. Philomena surpasses the 100 years prohibition and the 1961 liturgical directives technically has no hold over St. Philomena.
In closing, taking the statement of the USCCB that a "Saints is already a saint in heaven whether officially canonized or not" then St. Philomena and other unknown saints that the Church experienced difficulty in documenting their historical existence is not a hindrance for all the lay faithful to invoke their powerful intercession. And most especially in Heaven this saints are all glorious and cannot be dethroned.