I wonder if something like the radio/royalty model wouldn't work as a replacement for ads. You pay ISP, they are the "radio station" playing what you want to hear, they pay micropayments to all the sites you visited proportionally.

I can immediately see significant issues (user data, managing payments, admin, biggest sites get bigger etc.) but if there's a market demand for a new model, it wouldn't even have to be regulated initially. It could be a feature offered by an innovative ISP. A sort of patron model for general browsing.

My 2 cents fwiw.