We are getting 31" 4K displays this year that come close (doesn't have to be 250 DPI at desktop viewing distance, but the high 100s would be nice). They are expensive ATM, but should come down in price pretty quickly. The only question I have is if Windows and its application ecosystem will be ready for it? There seems to be a lot of scrambling right now to prepare for a new high DPI status quo, so I'm very optimistic.