Why He Can Win: Jackson punches as hard as anyone in the Light Heavyweight division. All it takes is one shot to end a fight (Silva, Liddell). We still haven't seen what happens when Machida gets hit with a clean strike.
Why He Can't Win: I can't see him getting through the fight without his lead leg breaking. If the fight goes on for longer than a round, he's in trouble.
Likelihood of Fighting: Barring an injury, Jackson will get the first crack at the new champion, probably in November or December.
Why He Can Win: A healthy Shogun has the all-around game to match Machida stride for stride. He's quick, has power, good in the clinch, can sub you on the ground. The only hole is, well, you know.
Why He Can't Win: Although he won the Liddell fight, you can't help but wonder about his conditioning. In a five round fight, it's tough to feel confident he won't gas.
Likelihood of Fighting: Rua needs another big win before he can be considered a title contender.
Why He Can Win: Griffin might just be crazy enough to forget about the Machida aura and take the fight to him. How will Machida respond to adversity in the cage? We don't know yet and it'll continue to be a mystery until someone pressures him. Griffin's submissions are also very underrated. We saw Machida get caught in a triangle against Tito Ortiz, so it's not far fetched to think it can happen again.
Why He Can't Win: He takes too many strikes. Griffin gets hit against everyone he fights. The other problem is Griffin is not a finisher. To defeat Machida, he'd need to win a decision, which means getting through five rounds without getting beheaded. In a three round fight, I'd like his chances a lot better.
Likelihood of Fighting: With a win over Anderson Silva at UFC 101, Griffin would position himself as next in line to face the winner of Machida/Jackson.
Why He Can Win: As much as they want to build Machida up as a superb wrestler, I think it's actually his one weakness. The problem is getting in without getting hit. Couture still has the wrestling ability to overpower opponents.
Why He Can't Win: When you get older, your reactions slow down. It's not dramatic, but the extra hundredth of a second it takes could be the difference between Machida's straight left hitting you on the chin or partially landing. Couture is just too old for this sort of opponent.
Likelihood of Fighting: It's a long shot. There are better fights for him at Heavyweight (with a win he gets Lesnar/Mir, with a loss he gets Cro Cop). Either way, I think Couture finishes his career at Heavyweight.
Why He Can Win: Like Couture, Henderson has the blend of wrestling and toughness I believe it will take to defeat Machida. He can take a strike and keep coming forward.
Why He Can't Win: Henderson and Griffin have the same problem. They do not finish fights.
Likelihood of Fighting: Slim. Henderson's future depends on his fight with Michael Bisping. If he wins, he's getting a Middleweight title shot against Anderson Silva. If he loses, well, then things get interesting. Henderson would probably make the move to Light Heavyweight for good, since he'd fall behind Bisping and Marquardt/Maia on the list of contenders. At 205 lbs, he'd still have some viability as a contender. Personally, I want to see him and Wanderlei Silva fight again.