You did say that they are becoming a "dinosaur", to me that means only one thing, obsolete, as in old, inferior, outdated etc.
What you are describing is a phase out by another competing technology, not necessarily a better technology at that. History is full of such examples where the market chose one technology over the other where the "looser" was actually superior to the "winner".
So plasmas are definitely not obsolete or a "dinosaur", but you are right that plasma may be phased out by LED's and other liquid crystal technologies on the horizon. I still don't think that plasma is dead, I know I would choose plasma over LED probably 9 times out of 10 and there are plenty of others that feel the same way, but in the end, the market will decide.