Here in SoCal, there are lots of cons. Most of which consist of typical movie, television, and promotional booths.
Even though I have not been in the hobby for that long compared to others (5 years), I can still tell that these are not the way cons used to be.
There is only one true convention that I attend. It is the annual Cal Comic Con run by Terry's comics, which I have found to hold the best dealers from around the country. It is my personal favorite con of the year, and only consists of 2 small rooms.
I think that conventions will survive as long as there are collectors to fuel them. They may not be like they are now, but lets be honest, true collectors only attend cons to meet the creators, buy comics, and socialize with fellow collectors/dealers.
Collecting will endure as long as there are enough people to keep the hobby alive.