This is overkill.
The Retina Display is gorgeous enough. I think a 2K resolution is already fine as it's over 300ppi which is incredibly amazing already.
The mobile market should consider doing more for battery life and their operating systems than upgrading screens every now and then. There is really no way you could actually see a difference. The Screen Tech should be improved, not just pixel density. It already peaked high enough.
I believe the mobile market peaked in terms of screen quality. Right now it's just a matter of taste whether you go for AMOLED, OLED or IPS.
OT : And for the PC market, PLEASE upgrade those ****ing 1366x768 type of crap. It's not 2003 anymore. I swear most laptops still have this crappy resolution. Mobile is the future but the PC market isn't going away so

bitches move!