If their business model is not sustainable that's their problem. Movies are big business and if theaters with over priced popcorn fail then Hollywood will still figure out a way to get people to watch it and then make money.
As long as people insist on going to theaters and buying concessions, there will be theaters.
Stop buying concessions and either:
1) theaters will have to find another revenue stream- parking fees?- or renegotiate their contracts with the threat of shutdowns.
2) theaters will disappear, and we'll all watch movies at home.
And 2 is FAR more likely. The question is, will people continue to see value in going out to see movies?
Personally, I don't go out to see movies that often. The last movie I saw in theaters was
The Avengers in 3D...and I felt the 3D wasn't particularly worth it. But my lack of going to theaters out isn't because I don't like movies- 'cause I actually LOVE them- or the prices, but because I when I go to the movies, I like to go in a group.
For me, moviegoing is a social activity.
And currently, the group I run with almost invariably goes to see movies I want to see on nights I can't go. Or they go with their spouse & kids. So I watch them at home...eventually. Maybe.