I've come to the conclusion that how well a game runs typically depends more on the game itself rather than the hardware.
For example, the ghost recon wildlands benchmarks I've seen really don't bode well for the less expensive cards, so if you want to stay confident in your card over the next few years, I'd definitely save a bit and go for the 1070. You'll likely end up loving a future game that's really hard to run so the extra power of the 1070 will surely be worth it to run everything maxed out and steady.
It's really quite a powerful card. I'm using my 1070 at 1726p (80% of 4k) to hit 60 fps on just about everything maxed out. It's awesome.
So an added benefit in case of the 1070 is that you'll be able to downsample from...