My DM has 5 adventure paths that are 3.5 that he wants to run us through. Since we meet once ever two weeks, he figures he has enough
material to keep us busy with 3.5 for the next 15 years.
At that time, he'll be 75, and who knows what the state of the game will be then (or the state any of will be in, I am not a spring chicken myself).
I do know that the cat is out of the bag with the OGL for 3.5, and the way that wizards is playing the 4.0 bag, I just don't want to keep on giving them my hard earned money.
They plan on making 'expansion books' ever year as part of the core rule book set. I'll stay 3.5.