Large displays generate their own high voltage, so it should be isolated to the display.

Wow, that's the first time I've heard of this type of issue with a large display.

Outgassing is also caused by contamination of the gas from microscopic particles being ejected by the electrodes during normal use.

Don't take my word for it but I would think this is correct. I believe the main objective though is to reduce burn-in like a screensaver on an old CRT computer monitor.

So at this point 128x32 plasma displays are now out of production? I'm assuming the same for the 192x64s.