Word of mouth. Of course spreading the word of new products and services would take a lot of time so some businesses won't be able to spend a lot of money and bootstrap to millions of customers in a few months. Everything would be slower but it will function.
So a future where only large businesses serving large segments of a market are able to operate with any success while small players have little to no chance in establishing themselves into small niches. And that's of course before getting into how you broke the primary method of monetization of the entire web.
That's how it would work if we remove advertising. But is there any chance of removing advertising from the world? I don't think so. What's happening instead is that a big player like Apple is using their existing base (iDevices) to build its own advertising platform and weaken rivals in the advertising business.