The term "retina" should be replaced with the word "decent", then there won't be a problem. Heading into 2016 all Apple computers should come with a decent display.
Hopefully they'll just be getting rid of the term all-together. I would imagine that next year's 21.5" iMac will be all-retina just like the 27" is now, and the Air will probably be EOL'd too. That would mean every Apple computer with a screen is retina, and we can stop using the term. Just like no one refers to an iPhone's screen as "retina" anymore; it's standard.