I'm not so sure about that, mainly because if they go back to what it was before where they use the characters from the main anime then they go back to restricting themselves. Basically it will have the same restrictions that movies 1-19 have being that all of the main cast characters(excluding Team Rocket trio) that aren't move exclusive characters have to show up and any pokemon they use have to be ones that they have with them in the current anime, and there pokemon can't evolve, or learn new moves, and they Ash and his companions can't get any captures that don't leave at the end of the movie.
This is because despite the argument of the movies being non-canon if they had any pokemon on the main cast in them that aren't from movie exclusive characters evolve or learn new moves, or one of the main characters like Ash gets a new capture then that would have to carry over to the main anime, meaning that people that don't see the movie will miss out on that team change. However the reason why this wasn't a problem for movies 20, 21, and 22 was because they were meant to be set in a different universe that was separate from the main anime.
So, while I'm not saying that it's impossible that they could have the next movie go back to the old format of having some connection to the main anime, at the same time I wouldn't be surprised if movie 19 wound up being the last movie that has any connection to the main anime that we got, because having the movies being completely separated from the main anime would give them more freedom.