Yeah the 1070 is rumored to be faster than the 980ti, which will smoke 1440p. Really the GTX 970 is fine for 1440p, and the $200 Polaris 10 card should equal its performance. Unless you want to run max settings everywhere.
Regarding your build, I suggest getting a 1TB SATA 850 EVO rather than the 256MB PCI-e. It's true that NVMe SSDs are incredibly fast, but you won't actually notice the speed difference outside benchmarks while the extra space will be very welcome-- you can put all your games on the SSD. You could even get a 2TB 850 EVO and skip the magnetic hard drive entirely, unless you need to store tons of media.
I would also buy the win10 license on Kinguin.net for $20, or simply activate it with your old Windows key for free.