It's been rumored that Amare is seeking a player option after the third year of his extension. It sounds like a good move for him, and it wouldn't surprise me if the Suns have to eventually cave and give it to him.
In this case, I think that "eventually" should happen sooner rather than later. There's no question that, barring catastrophic injury, Stoudemire will be worth a maximum contract, and that virtually every team in the league will figure out a way to go after him if he becomes a free agent. I supported being cautious with Joe Johnson, even though that turns out to have backfired. But the only sane choice now is to get the extension locked in as quickly as possible.
If that means giving him an opt-out in the summer of 2009, then so be it. If the Suns can't convince Stoudemire in four years that they have a winning future, maybe they don't deserve to keep him.