Well, I run Skryim maxed out (excluding AA) with the FXAA Post Process Injector and 2K HD mods, along with some severe LOD + Render Distance INI tweaking, and this is on a mobile GeForce GTX 660M with 2GB. I can't speak statistically for VRAM usage, but I can pull a good 30-40fps average with minimal slowdowns, which is more than playable, for me at least.
That said, I think you're limited a lot more by the GPU itself rather than the amount of VRAM made available. 2GB is about average right now - I've seen some titles use every last bit of it, and some others barely use any; I wouldn't say it's 'more than enough' for future titles, but for right now, I think you'll be fine. Remember that more VRAM on a low end card doesn't make it any faster, though - don't fall into that marketing trap.