I wonder if we'll end up seeing state actors (or supranational entities like the EU) promoting state funded networks as a public alternative, as is sometimes the case in industries that tend to be monopolistic due to the cost of starting - transportation, telecommunications, etc.
You make a good point but I'd like to think of it this way: If the said service is made mandatory, then it has a chance of succeeding. Else, building that critical mass entails a lot of customer acquisition costs that a Govt may just not be in a state to justify. And therein lies the beauty and danger of network effects. Once a company has them, it is very very difficult to dislodge it. Look at Visa and Mastercard: V has been around since 1958 and MC from 1966. Both are valuable as they have network effects.
We need to stop feeding the beast.
I'm still convinced that Opera Unite, which fused distributed social + web client + web server, should have been the way forward to make the web truly owned by the people: if social sites were simply caches of content available p2p or through any social site of my choosing (that the content owner allowed) ...