I think im not.
https://www.youtube.com/watch?v=xsCIdqIqbgM
Live benchmarking of a Titan X. "But it's a Titan X!" you cry - yeah, a Titan X that is outperformed by overclocked 980Ti's that he reviews as well. At no point does any game ever run over the 6GB Frame buffer of the 980Ti (in a later matchup review, he had to deliberately TRY to get games to even get near 5GB). The 980Ti will perform as well as a Titan X, unless you're willing to replace the stock cooler on the Titan X (as OEMs are not allowed to ship a Titan X with anything but the referrence cooler) with liquid or something. And even then.. there's a 980Ti Hybrid from EVGA with a hybrid water block that still blew a Titan away.
Notice - 60fps Ultra BF4, 45+fps Ultra with super texture pack on Shadow of Mordor. All perfectly playable, at 4k Ultra settings. If you stepped things down, shut off the AA alone (which is absurdly not necessary at 4k anyway), you'd probably be able to get 50+ fps on most games at 4k with a single factory OCed 980Ti. In a later review hes got benchmarks from Witcher 3 - upper 40 to 60fps, 4k Ultra. Again, step back the settings just a little (like turning off AA which is superflous at 4k), and you should be able to get 60fps. And even 4k running at merely "high" settings will still look a lot better than 1080p.
Pascal is supposed (at the high end) to be 35-50% more powerful than the Titan X, according to the people who have had hands on time with the engineering samples nVidia shipped. Since a Titan X/980Ti can handle most games at 4k all-but-Ultra now, i dont see why Pascal's top enthusiast card wouldnt be able to do better.