I had written a long post about how you shouldn't put AMD out to pasture yet. Then something happened and I lost it all. Here's the short version.
Nvidia Titan X is a beast, but it's also $1000. There's going to be a small market for that.
AMD keeps up well enough in terms of comparable cards:
http://www.hardocp.com/article/2015/...amd_r9_295x2/8
The price of AMD cards is finally back to normal after the coin mining craze artificially raised prices.
4k is coming, and will be a huge deal. The biggest thing to look for in cards for ultra high res gaming is going to be V-Ram.
The other major innovation that will make 4k playable will be Freesync/G-Sync. Freesync is AMD, an open standard, and will have no licensing costs. G-Sync requires Nvidia GPU and special monitor which adds ~$200 to its cost. This is going to be hugely limiting for people who want to get into 4k on a budget. AMD might very well win out, even though I don't think Freesync is quite as good as G-sync (I'll need to look up the specific differences more to be sure).
Same goes for VR. Whatever card can cater to the different VR hardware requirements is going to be at an advantage. Like G-sync/Freesync for VR headsets will be really important, with a minimum refresh and framerate of 75hz being incredibly important.