History sees the work of evil (Satan and his satellites) throughout salvation history and into our modern times. How could Christ has already closed it? Satan fun’s freeruns somewhat freely from the times of Genesis until now. The demons have seemingly always been coming and going. They nevertheless remain condemned to hell.
The demons not in hell, still take their Hellhell with them. The subject of hell is one not clearly understood. Hell could be a state or an actual physical location. We simply do not know everything. Fr. Gabriele Amorth, one of the most famous exorcists in the Catholic Church, in his book An Exorcist Tells His Story, that at the point of liberation of the possessed condemn the possessor to the Foot of the Cross. He make note that most exorcists condemn then to hell from where they come.