Isn't this sorta a bad idea for everyone involved? Big publishers having to jockey for position (especially if they stick to 10 at a time) or dealing with people who might vote "no" just out of spite, and indie games getting steamrolled by huge games? I dunno, this just seems like a weird move.
Big publishers won't have to do anything. Far Cry 3 and AC3 went up without Greenlight.
It would be insane to require that from established players.