Your quotations clearly state that Ellen G. White foretold a future time when "observance of the false sabbath will be urged upon us." Further, "All nations and tongues and peoples will be commanded to worship this spurious sabbath. This is Satan's plan..." I have put in bold two words that answer your question. Now, taking that as understood, I proceed from there.

Having some (but not all) the literature Ellen G. White authored, I do not recall her ever foretelling a time when all nations will become Christians. On the contrary, she repeats time without number the eventual demise of all nations that do not uphold the Seventh Day Adventist religion, but not only by insisting that the Fourth of the Ten Commandments be upheld. That is certainly the main one SDA adherents are known for promulgating, but keeping all of the Ten Commandments is deemed to be part of God's requirements.

A foundational teaching of Ellen G. White is that the most holy place in the temple of God was opened in heaven in 1844, and inside the ark was seen the two tablets of stone God had written the Ten Commandments upon. Here is what she says about that:

"Within the holy of holies, in the sanctuary of heaven, the divine law is sacredly enshrined - the law that was spoken by God Himself amid the thunders of Sinai and written with His own finger on the tables of stone.

The law of God in the sanctuary in heaven is the great original... Those who arrived at an understanding of this important point were thus led to see the sacred, unchanging character of the divine law... The law of God, being a revelation of his will, a transcript of his character, must forever endure... light was shining from that open door of the sanctuary in heaven, and the fourth commandment was show to be included in the law which is there enshrined." The Great Controversy, Ellen G. White, p.266-7, Advent Books (emphasis mine.)

A point of note here is that, in the view of the SDA, Catholicism continues to violate not only the law on God's Sabbath, but other laws, such as not having images etc. Thus they say Catholicism remains aligned with the beast of Revelation, having its mark. Making a demand for all people to observe a first-day-of-the-week sabbath would not mean genuine Christianity. As your quotes show, that is a false sabbath, one that Satan wants to be followed.

The chapter goes on to explain Ellen G. White's interpretation of the beast, and its mark (Rev.14:9, 10), declaring Catholicism to be the instigator of observing the 'wrong' day, and that Protestants who go along with that day "is an homage they pay, in spite of themselves, to the authority of the [Catholic] Church." (She quotes here from a Catholic document; see p.275 Ibid.). This means that even when (as SDAs expect) Rome will turn around and declare the first day of the week to be the 'official Sabbath day' that the world must observe, all who fall into line with that will (in her words):

"But when Sunday observance shall be forced by law, and the world shall be enlightened concerning the obligation of the true Sabbath, then whoever shall transgress the command of God, to obey a precept which has no higher authority than that of Rome, will thereby honour popery above God. He is paying homage to Rome and to the power which enforces the institution ordained of Rome. He is worshipping the beast and his image...

In the issue of the contest all Christendom will be divided into two great classes - those who keep the commandments of God and the faith of Jesus, and those who worship the beast and his image and receive his mark. Although church and state will unite their power to compel "all, both small and great, rich and poor, free and bond" (Revelation 13:16), to receive "the mark of the beast", yet the people of God will not receive it." (Ibid. p.276) Emphasis mine.

From this it might be seen that Ellen G. White was not thinking in terms of all nations becoming Christian, but of all who go by a legal decree issued by Rome and worldly governments to compel them to start observing the seventh day as a time of rest and worship, as receiving the deadly "mark of the beast". The SDAs claim not to be in that number, having the saving mark of Christ on them, as shown by this other SDA writer. Uriah Smith published his 700 page tome in 1908 and he agrees with Ellen G. White. Consider this tiny sample quote:

"And in this we find still further evidence that Sunday keeping is the mark of the beast... The beast also has a seal, or mark, which is his sabbath... Christendom will at last be divided into just two classes: to wit, those who are sealed with the seal of the living God

• that is, have His mark, or keep His Sabbath - and those who are sealed with the mark of the beast - that is, have his mark, or keep his sabbath.

"...the reader may ask for some evidence that a person cannot be said to keep the commandments of God unless he does keep the seventh day." and proceeds to give SDA evidence. (Daniel and the Revelation, U. Smith, p.587-8, Stanborough Press, 1908 Emphasis mine.

So, the answer to your question is "No", because it will be a false, satanic sabbath being enjoined on all nations, said Ellen G. White. It will be a great deception Satan and his visible agents will enact, so that agreement with it just won't come into it. "Compulsion" will be the key word. If you think dictatorship is already at work in some countries, "You ain't seen nothin' yet," according to the SDA interpretation of things.