I would advise strongly AGAINST putting a lot of money into a high end GPU right now.
There is an easy and very low-cost way out of this:
get a second hand GPU now, something mid-range-ey and comparable to R9 280x, grab a GTX 770 or something. Or go one tier higher perhaps to a 780/290. They're on sale everywhere, they are relatively young so usually without issues, and you can resell them for about half the price you bought them for in a year's time, when Polaris/Pascal have landed with complete line ups.
The thing is, if you wait for Pascal now, you will first be looking at a mid-range chip that is marketed as high end, just like the GTX 970/980 are now. You will have to wait for the big chip a bit longer, and since that is the level you want to buy into right now, it doesn't make sense to do that on an outdated process. Especially not if you're not one to switch cards on a yearly/bi-yearly basis. Therefore, get a cheap alternative to sit it out, lose very little money in the process (about 80-100 bucks for a full year of gaming - way less $/time played than if you buy into a 650 dollar GPU today) and you will be up to date much longer for only a very small premium.
In general I do agree that 'wait it out' is never worth it, but today times are different - we have been stuck on 28nm for way too long and it is being drawn out with very little performance gain since 2012/2013, games are catered to that performance cap, and VR + 4K + DX12 + process shrink + new games are around the corner. Not a single GPU is really built for that big step forward today, so waiting is now easily the wiser decision.