As it stands, you can have or the other. Not even two Nvidia Titan Blacks are enough currently. My advice, get a good quailty 2560x1440 and enjoy dat 144p.
The future—aka 4K gaming—is made up of very, very small pixels. After spending the past two weeks checking out games on Samsung's U28D590D 4K monitor, I'm still going to call 4K gaming the near future rather than the present. Yes, you can play games at 3840x2160 pixels right now. Yes, 4K monitors are becoming more affordable. But are they worth it? After spending a couple weeks using one, I can comfortably say: no, not yet. Even for a high-end graphics card (or two), 4K is too demanding for max settings and high framerates. If you're willing to play at 30 frames per second, though, 4K is a different story.
Oh and don't even think about running 4K on Windows 7.
Unfortunately, if you're still running Windows 7, 4K is a terrible experience, no matter what 4K monitor you're using. The OS isn't designed to scale to such a high resolution, and everything will be impossibly tiny unless you crank up DPI scaling to 125% or 150%. But that scaling is for text—it doesn't properly resize other UI elements or affect some applications like Steam. Chrome doesn't scale its text properly, either. Windows 8 is much better about properly scaling, and requires no setup to scale text, UI elements like Windows Explorer, and applications to 4K resolution. Text in Steam and Chrome is noticeably fuzzier than system text, but everything is usable and legible without constantly squishing your face up against the monitor.