He would have to get new knees, a vertical, better posture, more strength, lateral quickness,etc etc etc.
But while he may not become that, he could become a servicable SEC center that plays 20 minutes a game and forces other teams to change their offense and defense.
Aaron Gray or Roy Hibbert are perfect examples of a project post player that went from useless - inconsistently decent - excellent.
They were both 7'+ and neither were exactly light on their feet.
Both worked and developed into college players that were able to impact the game even though they were inconsistent as can be to start.
Im not even saying Riek needs to develop into Hibbert in terms of NBA talent. He just matches Hibbert in terms of size, heavy feet, and raw coming into college.