I don't see any reason why Mboup couldn't be one of them. I can see why others are skeptical though. If Demin, Catchings, Hall, Saunders, Keba, Mag, Fous are locks to make the rotation, that leaves 2 spots between Baker, Knell, Crawford, Koz, and Mboup. That's a lot of talent fighting for the end of the rotation.
That being said, I think KY is very much a "best player plays" kind of coach and, as much as we as BYU fans love the guys who have been on this roster, I don't think KY has any allegiance to any of these guys above any others. If anything, you could argue that the new guys who have been brought in definitely have a place in the system, where the inherited guys may not. So maybe there's a world where Mboup or Crawford make the cut over Knell or something, we'll have to see.