A GTX 1070 can currently max almost every game at 1440p / 60Hz. I'm still using a 980 Ti ( 1440p/60Hz) with slightly less performance than a 1070 and the only game I've had to reduce settings for is Mankind Divided. I've been threatening to upgrade forever it seems but I just haven't needed to.
That said if you're buying new and can afford it the 1080 is a more futureproof card.
Edit: Playing DOOM at 60 FPS max settings right now. Runs great!