Honestly, I play games RIGHT NOW at 1080p that use A LOT of RAM. Like BF4 uses RIGHT at 2GB if I use ULTRA settings with 4xMSAA. And when I used to have a 1440p monitor, I would get up to 2.5GB in quite a few games. Good thing I have a GTX780 with 3GB of VRAM.
So sure 2GB if fine for now, yeah. But within the next 2 years, you'll probably end up finding a few AAA games that'll go over 2GB at 1080p. You'll just have to lower your settings so it doesn't go over. OR you can get a 4GB 770.
But it's not that big of a deal, 2GB is FINE. I'd get the 770's over the 760's for sure.