"Plasmas are great initially, but you probably need to plan on replacing it every 2-3 years. LCDs should last longer."
I've heard the same thing about Plasma TV's except it was 5 years or less for replacement of a Plasma TV.
They are probably still usable 5 years out, so I won't dispute your comments. By that point, with heavy use, however, I would suspect that there would be a marked deterioration in the screen quality, and likely some screen burn from network logos.