Days of Future may have set Xavier back on the path he needed to be on, but if James McAvoy is to be believed? He will get pretty violent at the end of X-Men Apocalypse:
"At the end of this movie, you definitely see my character in a slightly different frame of mind, maybe being a bit more violent."
Now obviously, there could be a million reasons this happens. For all we know, Apocalypse controls him into being like this. But for now, we'll just have to speculate.
Also, McAvoy revealed he would be totally up for more X-Men films after Apocalypse finishes if Fox is wanting to do more.