Don't wait for 3D Vision 3.
I've got that epic Asus monitor with Nvidia 3D Vision 2 and there is really no reason to wait for a 3rd generation.
I've seen the first generation and own the second. The improvements were immense considering the darkness and the glasses.
There is no point to any Nvidia 3D Vision 3 yet, because the flaws of the first generation are practically completely gone.
I strongly advise you to skip this monitor though (although it is epic and awesome and many games that do not perfectly work in 3D can be unofficially patched - search for "helix Mod"). What you should be saving up for is the Occulus Rift. Haven't used one yet but the industry goes nuts over it.
My prediction is that Occlulus-Rift-like virtual...