65-inch Panasonic plasma from 2011 is still going strong here. I added a 4K television to our workout room a few years ago but still have not seen anything that compels me to replace the plasmas in our living and recreation rooms.
The newer televisions do indeed display more detail and appear brighter but our two plasmas remain enjoyable to watch due to the natural color tones and smooth tracking of motion. To me, it is sort of like an analog vs. digital thing. At some point, the newer technology will achieve excellence in detail, color, and motion and, a couple of years after that, Costco will sell them for about half the price they started at. However, for now, I am in no rush to replace our older units.