So what are you going to do after the 1080 comes out....
It'll be a bit till the next Titan comes out. Are you going to sit on Maxwell?
I have never ditched my GPU's after only having them a year and I won't start now. By the time I am ready to upgrade, I will have the cash saved to buy everything I want, and then whatever I get from selling my old stuff is just a bonus. GPU's are throw away products. I chose to buy expensive ones this time. That doesn't change the fact that GPU's are expensive garbage the instant you click "add to cart".
I suppose I could sell my 980ti's and use some cash I already have to replace them with 1080ti's, but the timing is bad for me. I am using Sandy-E still and it's IPC age is starting to show. I won't do another GPU upgrade with this chip. These cards are the last this CPU will see, at least with me as its owner.
I will upgrade to a Skylake-E platform and from that point I will upgrade the GPU's. Hopefully big Pascal drops right around the same time as Skylake-E. That would be great. The earliest I will upgrade GPU's will be with big Pascal and they might be timed right and the performance might be around double what I have now, so that would also be just about right for a legit upgrade.
That said. If BF5 lags this year, discard everything I said. I will buy new GPU's ASAP. ok ok, no I won't. But it will be tempting.
Also, I tend to stick to a single game or just a couple good games that I really like. I don't have the time to play all sorts of different games all the time. I get invested in just a couple and stick with them until something else really great displaces them. So, if my rig runs those games prefect, then I usually won't upgrade until a new game demands more power. I would likely still be using my 670's right now if I hadn't upgraded to 1440p/144hz.