I think he will be bought out or danny will use the stretch provision. It could be an ok situation for danny in that if he drafts one of the many talented sfs, they can come off the bench and compete with green , making him a better player or increase his trade value
Why on earth would Danny want to stretch GW's contract?
If we are planning to contend in 2-4 years, the value of cap room will be exponentially higher then than it is now.
I can see the possibility of stretching Wallace as part of a series of moves to clear the cap space necessary to sign a max free agent (or acquire one via trade). Even if the Celtics spend picks to move guys, it might be necessary to stretch Wallace if Ainge wanted to sign Carmelo Anthony (and Melo wanted to come to Boston).
I read the idea as suggesting Danny would want to waive him in the near future, and without any concrete plan for how to use the room.
If you're talking summer of 2015, sure, I suppose you can concoct a scenario when we'd stretch him as part of a deal that's the final piece of the puzzle, though I agree with Chris that even then it's hard to imagine.
But now, without such a deal in hand, it makes no sense to me.