I don't trust the 970 as it is now, or recommend buying it to people who might keep it for years.
It is true that the GTX 970 is not "perfect", not just because of the 3.5GB of ram issue (which in many games doesn't even play a role, by the way).
NEVERTHELESS (and you can believe I had my share on forums reading and debating this debacle) I did get a GTX 970 since IMHO it is still (rather) attractively priced and has all I want. A R 290X etc. was not an option for me (2x8 pin PCIE connector, how much power does this thing need?) because I never liked the ATI drivers, more heat, lack of PhysX and DX12.
Has the GTX970 a long future ahead of it? No it hasn't. Because no card has - in fact hardly ANY hardware has a long future. At the time when I got the 970 (just a couple weeks back) 6GB Nvidia cards were merely "announced", let alone available, let alone affordable. I am not a guy who spends €700-€900 on a Video card. But spending €260-€300 on such a card is still reasonable, and it makes it also reasonable to buy another card, say in a year or so when 6GB cards are out.
Despite issues I had with THIS particular card (it's on RMA now for various reasons) overall I cannot be happer. I like the card. But of course the rest of the system must match it.