> It's not going to happen, because airlines want to cram as many seats as possible, even in business class.

Obviously this seems far fetched, but Airbus seems to be pushing the idea of putting the bunks underneath where cargo would normally go. Not sure the FAA approval requirements to have people down there, but this wouldn't take up any existing seating:

> Airbus in April gave a glimpse of the future when it unveiled at a Hamburg exhibition the sleeping modules that could slot into an aircraft’s cargo compartments. The berths will initially be available on the A330 from 2020, and potentially on the A350, the company said.