I doubt that TV sales are dying or will die in the foreseeable future. What HAS died is the market for high priced premium "Brand Name" TV. 10 years ago flat panel TVs over $1000 were a mass market item. What changed is that great TV technology is now available for $200.
There is nothing at all wrong with the smart TVs put out by TCL/Hisense/Element etc. for prices that would seem to barely cover the shipping.
There will always be a few souls who are willing to pay 5 times as much for a performance increase that most viewers would not even notice. The same is true in audio. So yes...the market for and profitability of Premium brand TVs like Panasonic has dropped a lot. Any profit now seems to come from streaming services/platforms like Roku and Echo enabled TV...rather than the hardware.
As they should. I've been complaining about stagnating television progress in the same sort of light as stagnating CPU clock frequency improvements (they are happening, but just incredibly slow).
And it's not just TV's themselves, the display makers, the I/O industry, the bodies responsible for standards (now you have tons of "standards" and a bunch of segmentation. See the mess that I doubt will be unfucked with respect to HDR "standards" in the next decade for example).
Big boys aren't able to play on the ignorance of people as much. With the internet, more people are informed about their purchases, and not at the whim of salesmen on the floor of the TV section of an electronics store. As long as TV's like this
Vizio Quantum-X series exists, the big boys will keep having trouble, as even the brands thought to be generic prior, are slowly starting to creep into the high end, just without too much of a high-end price so much.
