We have to wait until there are enough people willing to shell out $5000+ for a 4k display. When we get enough people like that, then we have to wait until there are enough people willing to shell out $4000+ for a 4k display. When we get enough people like that, then we have to wait until there are enough people willing to shell out $3000+ for a 4k display. When we get enough people like that, then we have to wait until there are enough people willing to shell out $2000+ for a 4k display. When we get enough people like that, then we have to wait until there are enough people willing to shell out $1000+ for a 4k display. When we get enough people like that... you see that pattern here? When it gets down under $1000 the product takes off like a rocket.
I'd estimate another 7 years... but I believe more exotic forms of display will intervene before then. I'm thinking contac lenses and glasses with built in screens. They wont be 4k, but they wont need to be because they'll be right in your eye.
A stopgap solution is what I call prismatic bezeling, which in theory would enable you to place 4 or more 1080p panels together using the properties of a prism to bend the light at the edges so the screen appears seamless. I expected this technology by now. Folding screen tablets that look like a standard laptop until you open it and it folds out into a beautiful seamless 25" display. Or a phone that folds open into a fullsize tablet. (The holy grail of mobile computing.) Needless to say, I am disappoint...