I don't want to make a big deal of this but we predicted that someone would produce a 4K tablet, and today we learned that someone has: Panasonic
It has a resolution of 3840 x 2160 and, somewhat unusually, is 20" diagonally. Apparently it is thin and light. No price or availability has been given but we can say with some certainty that this one isn't going to fit in your pocket.
Watch your work
Despite the lack of portability, and perhaps because of its immodest size, we can see this being incredibly useful to film directors/DOPs/ cinematographers and anyone that needs a quick way to watch their work on something representative of a TV screen, but in 4K. For stills photographers too, this might be the perfect way to present your portfolio to clients.
Apparently while this is just a prototype, it is one destined for production.
Now if this could just come with a quad-HDSDI input...