I was thinking about how basically the whole entertainment industry relies on advertising as well as tv stations and basically everything.

I don't know much about advertising but i was just wondering about what would happen if the industry collapsed?

The advertising industry has already entered a severe slowdown. This is the reason why many newspapers are discontinuing operations. They have lost their advertising revenue.

With the quality of programing at an all time low it's only a matter of time before advertisers cut back heavily on TV ads too.