I dont see why he couldnt be champ again but, with so much young talent and the fact that this is his first gimmick to work well for him as a champion, Im gonna have to say its a LONG SHOT!'
Think about it. Even wrestlers that keep a certain gimmick for awhile once they hit it big (ex. Stone cold, Hogan, Rock, Cena, Orton, etc.) even evolve with the times and change a little. And even though I think he could do that, I dont see it happening. His gimmicks are generally bad and even though "the Hall of Pain" thing works I feel like it would take too much time and effort the WWE doesnt want to put into him to re-package him just enough to be relevant. I dont think he will fade off into obscurity but i can see him as a VERY low main-eventer or high midcarder the rest of his career.
SIDE NOTE: Did I read wrong or did the 2nd post say Henry had the best title reign all year?!?!? Did you watch WWE in 2011?!?!?! Dont get me wrong, he had a great reign and longer than most in WWE this year (ex. Del Rio, Christian, Mysterio). But really best reign all year?? He only had two opponents his whole reign Orton and Show, and while the Orton matches were good and the ring collaping was cool he didnt really have many main event worthy matches this year. Cody Rhodes has (in my mind) restored the I.C. title to its former glory and is still reigning champ. CM Punk won both is 1st AND 2nd WWE titles this year, along with becoming Undisputed WWE champion and is still reigning champ. Dolph Ziggler was the best U.S. champ I think possibly ever and had a great reign. Edge ended his career on one of hid best title reigns earlier this year. If you consider Kane's World title reign(that I think went just into 2011) that was his best title reign ever and one of the longest and best in recnet memory. Orton's world title reign just before Henry was alot better also. I might even put Ryder's title reign higher just cause of the stories and matches it delievered.
OVERALL: great talent and hard worker and glad he got a good title reign but I don't see it happening again anytime soon.