People confuse the difference between perceptible and optimal. So ya, to see every pixel on a 4k screen, it needs to be pretty big (or you need to be pretty close). However we should stop wanting that. Computer monitor have too long taught us that we should work at a resolution where we can make out each and ever pixel. Rather, the individual pixels should be so small that they are completely imperceptible under any circumstances. That requires a lot more pixels.
As for your other requests, have you done any research on what is available, and the difficulties of what you are asking? This is the real world here, there are real engineering challenges. Let's go one by one:
Rec 2020: That requires laser illuminates. Since the primaries are points along the spectral curve, you have to have monochormatic light sources, meaning lasers. You can get that from laser projectors currently, if you are willing to pay, no consumer displays. Of course it matters little since there is no Rec 2020 content. However you can have a DCI display no problem, the Panasonic 4k displays are just shy of a DCI gamut. Oh and Rec 2020 specifies an 8k resolution, by the way.
5k Brightness: You don't have a power plug in your house sufficient for that kind of brightness, nor would you want to crank a display that high. Go have a look a commercial displays sometime, go see one of these things turned up to 700-800 nits. They are painfully bright in anything but a very brightly lit space. We are talking stuff made for direct sunlight usage. You don't want that in your home. That aside, you'd need a massive amount of power to deal with something like that, and noisy cooling fans to go with it.
10000:1 contrast ratios: You can have that right now. High end LCDs pull it off with backlight dimming, OLEDs can handle it as is. You want an LCD that does it static? Not going to happen, and a basic understanding of how blocking technology works will tell you why. Emissive screens like OLED can do it without much trouble, but of course you are going to have real issues if you want a high bright display out of those since brightness is a killer for emissive technologies.
Seriously, less with the silly whining. If you truly are interested in display technology, go learn about it and the limitations and issues. But don't just bitch and act like people should be able to magically figure out a way around tough engineering challenges. If it was easy, it'd be done already. If you think you have a solution well then, get on that. Go solve it and make a bunch of money.