Plasma still looks better than LCD etc, so I don't think they'll disappear.
Larger sets are already on the rise, and have been for a while now. Pioneer's 60" sets sold at least as well as their 50" sets, at least they did in our store. We couldn't get enough 60" sets to fulfill orders, and we now can't get enough 65" sets to fulfil orders. And that's just Panasonic. I'm sure the likes of Samsung and LG will have 60"+ sets at very cheap prices - they'll flood the market because when people buy TV's, they tend to buy the biggest they can get, regardless as to whether they're too big or not. And to be honest, for 3D to be effective, people will need the biggest set they can get anyway.
I'm hoping there will be a plan rolled out for 4K2K, with more products shown to the public and press than this year.
With that may come the next video format, which I still believe will be disc based - streaming 4K2K with HD audio just isn't going to become viable for a long time.