trio1989 :
what about all the next gen games that are going to be released as i am planning to keep these cards for a couple of years + i am gaming on a 55inch LG smart TV?
The size of the TV doesn't matter, just the number of pixels (1920X1080). 4GB costs about $50 extra so you are looking at $100. All I can say is it is up to you. Memory requirements go up when you crank up the anti-aliasing and other visual goodies. You could always crank the display down a bit if you do run into memory limits in the future.
Another point is, except for heavily modded Skyrim, by the time your graphics are actually using 2GB, your graphics cards will be struggling. A careful study of this was done and they found that even two 670's in SLI were not powerful enough to use over 2GB in memory, the FPS dropped to 20 or so by the time the memory was used up. Of course your SLI GTX 770's are far more powerful so I think they could drive over 2GB if in SLI.