The general consensus appears that free agents Bobby Abreu and Jason Giambi will be allowed to leave and that fits a logic.
The logic being, you have Xavier Nady, Johnny Damon, Hideki Matsui, and Melky Cabrera all under contract ... not to mention that Jorge Posada is old and working his way back from injury (so he'll likely have to DH some). The DH and OF positions are all taken care of. As for 1B, well, Teixeira is sitting there on the free agency market. He's younger and better than Giambi, and he'll command a pretty penny this offseason.
Look, with the pitching staff en route to containing Chien Ming-Wang, Phil Hughes, Joba Chamberlain, and Ian Kennedy, it makes sense to move towards the future ... especially after failing to make the playoffs for the first time in a millenium this year.
Adding Sabathia and Teixeira doesn't make the Yankees too old, as neither are 30 yet.
It's hardly a full-scale youth wave, but we are talking about the Yankees.