There are exceptions for every rule, and I'm sure to some people this whole thing will have a bigger impact (mostly SLI users), but overall I believe most of the refund intentions are knee jerk reactions.
Aside from the fact that upgrading a 780 to a 970 doesn't strike me as a smart move (all due respect, you do what you want with your money) if you are looking for future proofing, if you are right and in the next two years we will see "a ton of games that push well over 3.5 GB requirements for Ultra textures", then ops, I guess suddenly the 980 will have a problem too. Like I said, 4 GB isn't a magic number, and if a "ton of games" will push well over 3.5 you can bet that a lot of them will push over 4 GB too. See how it goes? Suddenly the 980 isn't future proofed either. I mean, if some games are already pushing 980's 4 GB to it's limits, like some people are saying, every PC gamer should start getting worried right about now.
I guess I'm just saying that if you guys think you won't have any future proof with the 970, then the same can be said about a 4 GB 970 and even a 980, speaking in terms of VRAM. The difference just isn't big enough to put one in the "not future proofed" category and the other in the "future proofed" category.