Dana White was very vocal in his desire for Chuck Liddell to retire from the sport. He claimed the Iceman had nothing left to prove and shouldn't even bother stepping into the Octagon again.
Why doesn't he have the same rap about Randy Couture? He's retired before and came out of retirement when he saw a beatable (in his eyes) heavyweight champ in Tim Sylvia. He defended his title, had his contract dispute and then lost his title to Brock Lesnar. What does Couture have left to prove? He's an MMA legend and former champion, and other than his bout this weekend with another MMA legend, Antonio Rodrigo Nogueira, there's not much left for Couture at the heavyweight level.
There may be other interesting fights for Couture, but he certainly shouldn't stick around to be the gate-keeper of the heavyweight division, assuming he loses. We don't need to see him fight Cain Velasquez and Junior Dos Santos. A fight with Mirko Cro Cop could be interesting, but both are past their primes.
Couture has stated he would go down a weight class to fight Lyoto Machida if the UFC was interested, but I don't think that's realistic. The light heavyweight division is deep enough to keep Machida's plate full of challengers. Although that might not be a bad way for Couture to fade into the limelight.
He has one fight left on his contract after UFC 102. If he beats Nogueira, let him go out with a title shot against a man he can't beat. Lesnar is only getting stronger and has already defeated Couture. Still, Couture is a big draw and that could be an interesting fight, promotion-wise.
Either way, Randy needs to start thinking about the end game. He's still one of the best heavyweight fighters in the UFC and can still fight. But so can Liddell. Couture is 46 and, like Liddell, has nothing left to prove.