If paywalls don't work, and ads don't work, some kind of metered-browsing would be a solution. It's so far away from happening, it's hardly worth discussing, but imagine this:

* let's say soundcloud could charge $.0001 (or something) for every pageview (or play, or some other interaction that the website chooses)

* this fee is mostly transparent to the user, they've signed up once, and have access to all metered sites

* the user would deposit money in an account ahead of time to use for the metered sites

* the metering could be built-in to web browsers to display when you're on a metered site using a standard graphic (like how the lock is a standard symbol for a secure connection)