The main point of a fast monitor is for gaming. 144hz doesn't look that different from 60 for everything else.
Given a single 980ti isn't enough to run 4k @ 60hz at max settings for most new games, I'd suggest the fact that you'd want 2-3 980ti's extremely prohibitive. Hence, it's going to be awhile before these come out.
Yes, you CAN run 4k@120hz from a single 980ti. You also CAN put tires from a Prius on your new Ferrari.