The problem gets worse – I can’t design for 1x on my Retina Macbook Pro. It’s impossible.
As Wells says later, the solution is for designers to keep a 1X external screen around for a while. Wells thinks this will only be possible for a short time as Apple aggressively kills legacy compatibility, but I bet it’ll be a pretty long time before Apple’s computers can’t even output with adapters to any widely available 1X monitors.
The first time I worked with a web designer, in 2004, he had a giant, old, mediocre CRT on his desk next to his nice LCD so he could ensure that his designs looked good on older monitors. We’ll be doing the same thing for a while with 1X LCDs. (By the way, designers can still connect a CRT to a Retina MBP for $30.)
But we don’t need to wait until everyone stops using them before we stop caring to fine-tune our designs for them. After all, people still use CRTs today, and we don’t care anymore. The people who still use them probably won’t notice, or at least won’t care, if something doesn’t look exactly ideal.
The same transition of not needing to care about legacy support for 1X displays will almost certainly happen long before we lose the ability to drive one from a modern-day Mac. And until that transition occurs, which is probably at least a decade away, responsible designers are going to need to keep a 1X monitor around and be willing to buy a few adapters along the way.