Young Beast (Nicholas Hoult) may very well show up in Apocalypse, and honestly, why not? After all, not having Beast around would be a wasted opportunity as the story arc of Apocalypse could very well include his dark and twisted alternate self, The Dark Beast. In the AOA timeline, Dr. Henry McCoy is a twisted scientist, performing experiments alongside Mr. Sinister on captive mutants that have been enslaved and imprisoned in Apocalypse's "breeding pens." It's his experiments that greatly augment and perfect Blink's abilities and also lead to the depowering of Polaris. His escape from his timeline to the mainstream one results in the creation of The Morlocks and for a brief time, he even impersonates the main timeline's Beast. That storyline could easily happen in Apocalypse, with Dark Beast traveling to the 80s and infiltrating the X-Men for Apocalypse by impersonating their Beast. Because of the close bond between Mystique and Beast (and even Beast and Professor X.), he would eventually be found out and the film could even deliver an interesting one-on-one fight scene between the shape-shifting assassin and the fur-covered creature that we haven't seen in any of the other films.