No fighter is going to go from a PPV show to living in a house for 6 weeks with no outside contact. Can you really see Roger Huerta going from the Sports Illustrated cover to living in a house with 15 other dudes?
They could totally re-vamp the show and have it as a tournament-style fight broadcast. Every episode would look like a "Countdown To..." episode, with the two guys fighting at the end. I think that would get pretty old.
Think of the Ultimate Fighter show as an episode of the Real World, but they get to beat the shit out of each other at the end.