I thought that a while ago. It hasn't happened yet but that doesn't mean it won't. And even if it doesn't implode, it could certainly decline significantly.
A HUGE amount of the "free" services and content that pretty much all of us take so much for granted around the web are directly or indirectly supported by online advertising. Take that away and, as you say, it will be interesting.
Gmail? I'd pay for. Netflix? I already pay for. Online content? Sure, I'll pay a few bucks a month for the Economist or the NY Times. I already pay for Evernote, Flickr, etc.
A HUGE amount of the "free" services and content that pretty much all of us take so much for granted around the web are directly or indirectly supported by online advertising. Take that away and, as you say, it will be interesting.