I don't think Green extends our window because we will soon see the games of multiple key players quickly deteriorate.
What makes you think that?
If anything, they are proving to very slowly decline, if at all. Look at the Big Three's numbers since coming together. KG obviously had a decline the past 2 seasons because of injury, but his rebounding/defense is right were it was in 2008. He is still extremely efficient. Ray may be having his best season in green. Pierce's number haven't changed significantly at all.
Age ain't nothing but a number.
Even if it is a slow decline, it is still falling back to the pack. The team will end up with a bunch of average players who can contribute to a mediocre team and who will be even more injury prone.
If the window we are talking about is chances at a championship, Green doesn't really extend that window. First, Ray and KG aren't even under contract past next season and Shaq and JO will almost definitely be retired after next season. Our window, with or without Green, would still depend on KG and probably Ray staying on and performing at a high level.
What Green does bring us is hope that we might still maintain a willing record post KG retirement, when Ray may no longer be on the team or may be here coming off the bench with lesser contributions. Green increases the chances that we can transition to being like the Wizards when they had 3 all star level guys and a winning record, but were never actually contenders.
I expect a domino effect as guy age since any one of our starters losing effectiveness will mean that opponents can concentrate more resources on stopping the ones that are still effective.
What would truly extend our window would be Rondo developing a jumper a la Parker. That would make him unstoppable on offense and a transcendent player considering how good he is at everything else.
That's crazy if you think Green helps our chances of becoming the 2007 Wizards. Rondo and Green are both more talented than their three. Arenas and Jamison put up nice scoring numbers, but gave up just as much. Rondo is an excellent defender and facilitator and I expect Green to become a very good defender at SF.
Rondo has already been working on his jumper and there has been a slight improvement. It won't ever be silky smooth, but it can become average.
There's no basis to your argument that Ray won't be just as productive on the offensive end in 2 years as he is now. His may not be able to guard his position all that well, but he will still be able to get open because of his conditioning, and his shot will be there when he is 50.
KG will need help on defense as he enters his late 30's, but his offense is predicated on picking his spots, when Rondo drives and kicks out or when he has a clear size advantage in the post. His ability to alter shots, defend the pick-and-roll, and help defense will still be better than average as he ages. His rebounding and man-to-man defense are the only two things I can see markedly declining after this contract.
They will decline. All players do. But these two are in especially good shape and put the work in to defy the odds.
You're simply being pessimistic. I'm guessing you were one of those guys who wanted Ainge to move Ray at the deadline last season and blow this team up then.