I hope Danny trades him this summer. His stock is high and the C's need to get younger. If I were Danny I'd be calling Donnie Walsh. He is likely to blow up the Knicks and good players could be had for a pro's pro like Ray.
My trade proposal:
Ray
Perk
Scalabrine
for
Curry
Crawford
Jerome James
I think Curry is an upgrade over Perk (not defensively, but overall), Crawford is close to Ray plus can handle backup pg (and younger) , and James gives us a backup center. 
Heck Chief, this is the kind of trade that only Isiah Thomas would do... if he was the Celtics GM! Curry is a very fat man that gives the opponent twice whatever he scores, Crawful is a ballhog who can score, but very inefficiently, in very bad teams and Jerome James can't play anymore.
Going to the point: I think your reasoning is flawed when you say that "the C's need to get younger". At this moment, we don't. We just need to get better.
How are we going to get better? We have an aging team that is over the cap. This year is as good as it gets. And my guess is, we will lose 2-3 of our rotation players. PJ, Cassell, Tony, Eddie, and Posey might be retired or on another team next season.
We can get better via:
1. This core has been playing together for a single year. Teams improve as their core bond and gel.
2. Our youngster (Rondo, Perkins, Powe, BBD) are still developing. Probably, they will be better next season.
3. House and Posey might go but they might stay. It's even possible that they might stay with non-Bird exception contracts. In that case, we'd be able to add 2/3 new FAs using the MLE and the LLE. If that happens, we'll have a stronger roster.
4. Even if they leave, that we'll leave us with the MLE, the LLE, 2 rookie contracts and multiple veteran minimum salaries to grab new players. Well, that's exactly what we used to get them a year ago.
Finally, we are the champions. The others must be more worried to improve. What I'm sure we can't afford is to regress. Trading Ray Allen for lesser players would do that. What's exactly the point? When you have players like Allen, Pierce and Garnett, the goal is to win it all. We have a chance to do it next year. Ray just averaged 20 ppg, 5 rpg, 3 apg, 1 spg, 50 FG%, 52 3P% and 87 FT% in 41 mpg in the NBA finals while guarding the so-called best player in the universe for most of the time. Find me someone who can contribute this way and I'm all for trading him.
Once again: I have no problems in trading any player for same value/better players. I will have no problems in trading Pierce (ergo also Allen or KG) in the future. But what's the point of turning a contender into a pretender right now? That deal would make us far worse right now and it wouldn't even improve our salary situation for the future.