There are self-cleaning public toilets in many places these days.
I think it would be possible if the right suppliers set their minds to it. I guess it requires the spraying and drying technology and that won't exist until the bathroom hardware itself exists, and that won't change until the spraying/drying is an option.
I recall that Buckminster Fuller tried to build that sort of bathroom: the idea was that it'd be basically a one-piece metal thing with no seams or cracks for mold/dirt and all rounded corners, so one could just spray it down. I guess it didn't work for the same reason a lot of his ideas never got picked up.