I think that if Rondo had been at full speed Games 4 and 5, we could've very well been going back to Boston up 3-2 for a Game 6. Given that fact, I don't think that we lost this year because of age, I think we lost because of a hurt Rondo.
And that's a problem that can be solved next year.
Because of that, I think we can still be a contender, but I think it'll take a few things:
1) The Big Three stay healthy and don't take major steps back.
2) Rondo fully recovers and actually improves his game.
3) Green and West stay and become better integrated.
4) We sure up the 5 spot.
These are big questions and big IFs. However, if those things happen, I think there's a chance we can still win one more title.
I wouldn't put money on it. But it's possible.