Don't doubt it, I'm getting 60fps roughly everywhere with DSR 4k on a single overclocked GTX 970.
Which has to work quite a bit harder than native 4k
So I'd imagine a native resolution 4k would have no problems with it. (my 4k screen will be here in a few days)

Remember to turn on the Occlussion culling.
Turn off FXAA absolutly, you totally don't need that at 4k.
(2 other options that you can mess with which hit the FPS hard but don't impact the looks very much are HDR, and Screen Space ambient Occlusion. sometimes changing transparent lighting can give a nice boost in fps also)


I'd be expecting better performance come DX11.