The biggest CRT ever made: Sony's PVM-4300

I'm kinda curious if CRT technology advanced to the point where a TV like that would've been possible at a better weight and price tag? I assume that CRT technology development stopped decades ago, but could we have e.g., replaced the heavy glass with some plastic-like material to save weight without compromising the picture? And are there any heavy components in the mechanism itself (Coils, Magnets?) that would have had alternatives?

I know it's just theorycrafting, but I do wonder what kind of CRT someone could've created if it wasn't for market economy forces.

I remember reading somewhere that there was this wild prototype flat CRT where the electron gun was at the top, shooting down, and the beam did a 180 degree turn at the bottom before being deflected into the surface of the screen.