Will 51,200 or 102,400 iso soon be the new 800? You'd better believe it.
You'd better not. The shot noise is physics reality. If you keep the Bayer design, there is about 1 stop left for improvement. Then you need a quantum perpetuum mobile for more. Again, the shot noise is not due to some deficiency of the current sensors - it is a part of the image itself, like it or not.
Removing the Bayer design would add another stop or so, roughly speaking. And that's it. There is a hard limit, which no human ingenuity can overcome. Like the speed of light, or the energy conservation laws. Unless some new Einstein comes and shakes everything we know about physics, there is not much room for improvement.
There is a lot of room for improvement however in the read noise (but below some level not so practical anymore), and long term read noise. But you do not need new inventions for the former, the dark side had it for years. The read noise affects the image mostly into the deep shadows but also creeps into the midtones as well.