I would introduce Mystique and Destiny's team in a post credit scene setting up a Captain Marvel sequel where they are her villains and yes, I would have Rogue steal her powers(only the strength and flight, though, not the Binary powers), but it seems like CM2 will be in outer space(and basically a prequel in terms of set in the time between her first movie and Endgame), so we'll have to wait a while for them to appear in CM3. Which is probably for the best, as we need to let Fox-men's Mystiques fade from memory.