Linux

I think you'll find that things will change drastically, yet stay the same in some respects. When hardware changes enough, and it will, the OS will change as well, and so will the UI.

Watch pure and applied science research, and you'll see emerging technologies racetrack memory/storage, solid-state quantum computing, etc. Don't look only at vendors for the future of technology.

But yes, in some sense technology marches in place as far as products go. There have been radical changes in technology that lend themselves to the status quo - better and faster, but "contemporary" hardware is the result. (Look at the history or hard drives, for example.)

Basically all the people who believe or simply require the old one, have to die, before the new one get's embedded. This sort of chnage is at a fundmamental level, lets face it windows with rounded corners, or true-colour, even resolution meant all sort of twiddling for those who wanted to bridge the gap between one 'tech' and the next.
So not it isn't stagnating, it's simply that for every step change in a technology, you need to implement a ramp, or a lift, even a catapult ( ), and that slows acceptance of the new tech.