We don't really need a self-important dolt to tell us why theaters aren't successful. There are hundreds of ways to dissect this problem and hundreds more ways to get creative in order to attempt to solve it and give a worthwhile experience/value to a movie-goer, but that's just a whole lot of words. Here's the bottom line:

What To Do = ( Home Experience > Theater Experience ) ? Stay Home : Go Out

Why don't we also ask Ebert to explain why Video Arcades died out as well... please, someone explain this!