Flyweight - With how shallow that division is, I don't see Mighty Mouse losing his belt anytime soon.
Bantamweight - Cruz is light years ahead of everyone in that division, except for maybe Barao. However, I believe Cruz will beat Barao and that will leave no more worthy contenders that actually pose a threat to Cruz. He's keeping that belt for a looong time.
Featherweight - Do I even need to go into detail with this weight class? No one at featherweight has the skills to beat Aldo, and for as long as he stays at featherweight, he'll remain champion.
Lightweight - Benson is just too big, strong and well rounded for anyone at lightweight, he's keeping that belt for as long as he wants. I do however believe Frankie won their 2nd fight though.
Welterweight - GSP is the most well rounded fighter in the UFC today. Everything he does, he does to perfection. He is the definition of a true mixed martial artist and I guarantee he'll retire with that belt.
Middleweight - Silva will never be beaten at middleweight, end of story. Some people believe Weidman is the man to dethrone him but to be honest I don't really see what Weidman brings that Silva hasn't dealt with before. Its the same story everytime Silva fights, "oh this guys definitely the guy to beat Silva, he's got this and he's got that." but yet Silva wins every single time and makes you feel like an idiot for actually believing his opponent stood a chance. Weidman will be no exception. I do however believe that if Silva was to move up and fight Jones, only then would he lose.
Light Heavyweight - Jones will run this division forever. He is the greatest talent and most dominant champion the UFC has ever seen. No one, absolutely no one is going to beat him at light heavyweight.
Heavyweight - Cain proved in the second fight with Dos Santos that he is infact the much superior fighter and is skill wise so far above anyone in that division. He also proved that Dos Santos only has a punchers chance to beat him, if he can't land that knockout blow, Cain will dominate him. Personally I believe the person with the best chance at beating Cain is Werdum, and I still think even he'd lose pretty decisively to Cain.