Printers have always handled higher resolutions than computer screens. So displays are effectively catching up to printers, not the other way around. An image has always looked fine on a screen at 72dpi. To print, it has needed to be 300dpi to appear in good quality and the same size. Most high-end printers will handle much better resolutions than that.
The Retina displays just give image professionals (eg, photographers) a way to better preview their work on screen before committing it to print. Really, it's software support that will be crucial (Adobe is already on board).