Remember when 3D was the hot new thing in TV? Your set was OBSOLETE if it wasn't 3D. Well the market sure killed that. I just did a 3D TV search on Amazon and ONE 3DTV came up, old stock from 2012.
4K will fare better. On the hardware side, the 720p low-end will go away, the new low-end will be 1080p/"full hd" and the norm will become 4K. Programming will catch up, mostly, not all programming is even 1080p at the moment. I will buy a 4K TV at some point... when one of my 1080p screens die, now that prices have come down.
Cable is the worst deal in programming. I set up my HDTV antennas and was blown away by how sharp the picture was on the local news broadcast. I already had 2 settop boxes and subscriptions for them. Then when I called Comcast to cancel everything but Internet I asked them what resolution/compression their HD programming was in. I immediately got a scripted response of "OK I'll look into that but first I need to..."
"no I need to know what resolution"
"but first"
"no I need to know what resolution"
"but first"
Then I canceled cable programming.
A friend has a Fire TV stick with apps loaded that get "free" local broadcast channels. They are rebroadcasts of TV stations from hobbyists and sketchy outfits. When one App content dies or the App gets kicked off the Fire TV stick, he gets another. I guess this is OK if you're really cheap. The resolution is roughly 480p and there are significant lags and glitches. I'd rather pay for Hulu and get decent streaming content in 1080p, but he is more budget sensitive than I am, and more thrilled about the bargain of getting local stations (circumventing the broadcaster's and FCC's blackout areas) from anywhere. I get all the local stations that are local, from 2 states, but I had to climb up in the attic to do so. No lags or glitches, though.