Been thinking about this for a while and trying to think who I really feel has the potential to be the next great fighter.
I think, for me, the answer has to be Frankie Perez. He just had another ridiculously dominant performance in the Ring of Combat.
5'11" and fights at 155. He's already a beast, but once he fills out he'll be even better. Trained by Ricardo Almeida and now 4-0.
I haven't found a video of his last fight, but here are two videos of him (one grappling video and one MMA video).
Submission! Frankie Perez vs Taylor Costantino at Grapplers Quest Beast of East 2012 (via GrapplersQuest)