I bought a GTX 1080 a month ago, ( my GTX 970 is still for sale, just sayin' ), and that is powerfull enough to run every driving sim I have ( rF2, AC, PC, PC2, AMS, Dirt Rally, R3E, GTR2 and P&G), on maximum settings with 50 cars, darkness and bad weather etc and still get over 100 fps.
Other games in other genres other than car racing, like Witcher 3 etc that will supposedly benefit from the new card don't interest me at all so I'll be staying with the 1080 for a few years yet