I honestly think the only way this could work is like email. So you either take the gmail like privacy destruction and ads, or you pay for a service. Back in the day it was bundled by the ISP, but now I think it's way more likely to end up being some bundled 'online service' company that for a monthly fee provided a swath of federated content and services. But that it hasn't sprung up implies that it's not a workable model.