If OC'd it will be fine. However I don't think 4k is really going to come down much until it becomes mainstream and to be mainstream it needs to be playable at decent rates on a single GPU. My guess is we will need to wait until at least another generation or two of gpu's as we are so far off a single gpu really being up to the job.
The other thing holding up the price of 4k is what will be the next high end item when 4k is mainstream? Without another high ticket item the manufactures have no reason to drop the price.