One concern many people have about plasma TVs is their relatively short lifespan. And until recently, it was commonly thought that you'd only get a few years out of your plasma screen before it was destined for the junk bin. But now it seems you could hang onto that flat-panel a good while longer.
Unless you watch your TV all day, everyday, you're looking at a around 42 years worth of normal use, according to Panasonic. "Normal" use is about six and a half hours worth of viewing a day. That's a significant increase from the previous notion that plasmas can only last "a few years."
That being said, I highly doubt a 2008 TV will be in tip-top shape in 2052. You might still have a picture, but I'd imagine other parts would suffer wear and tear.