With GW2, you get what, 1 beta weekend a month from now until release, which could be the end of the year for all we know. Not a good plan.
Ahhh... well... there are other games that I plan to play as well. Like the awesome OFFLINE SP game Skyrim, which I have many more hours to go. Fills the D3 OFFLINE experience for the time being. I can also play Torchlight OFFLINE to fill a Diablo style itch (I still haven't finished that yet).
I'm sure that the GW2 beta periods will come and go, and when they are around we will play the game, report bugs, and have fun. But, as far as online coop, GW2 is the next game we will be jamming in.
I won't go as far as saying I'll never buy D3, but, definitively not anytime soon. A bunch of people I game with feel the same way after the stress test weekend.