Retina all the things: it's a long term investment.
Unlike number of cores, processor speed, GPU power, RAM, HD or SSD sizes that keep growing, once we don't see pixels anymore, there's no need to increase resolution again.
The switch to HiDPI resolution is not just another marketing gimmick to be replaced next holiday season with the next.
It looks to me like the first time a computer technical spec reached a level where it doesn't make sense to improve it anymore. Unless we upgrade our eyes...