The only chance for anyone is landing a big shot like Serra did. George outshines everyone by miles when it comes to overall skill.
There are so many users out there who don't show visual signs and guys who have slight visual signs but aren't using that it is just too much of a gamble to make assumptions based on looks alone. Change in looks, change in weight, and the biggest one - change in facial features, are the best visual clues, but even they are not by any means sure bets.
As for the original question: right now it looks like as long as he wants to, because there is nobody who seems like they are good enough to beat him, or even anybody who looks like they have the potential to beat him once they fulfill their potential. That being said, fighters can come out of nowhere in relatively little time; it's impossible to guess who will come from nowhere in a few years and look like a champion in the making.
Do you really believe this UFC will be as big as it is currently.Too many mediocre events and too many shows in general will bleed this just like the ols WWE model.I give it perhaps 2 more years and then it will be on to the next big thing.
There is nobody to challenge him for the next few years at 170. After Shields it will be more pointless rematches.
Are there even any WW prospects that are coming up to potentially dethrone him? I can't think of any. He could rule the roost for the foreseeable future. Which i would do.. if i was him. As much as i would like to see him fight Anderson... he doesn't need to go to 185.. some guys up there will dwarf him.
Im no MMA expert but one thing I can say is its so easy to lose in this sport a fluke punch a fluke submission a big kick upstairs You can completely dominate a guy take him down and the guy twists your ankle funny and its all over plus nobody has really dominated for a long period of time the UFC titles change hands often Cera had the mega upset years ago is it impossible to think a guy flukes him outta know where again