I've been trying to come up with a concise way of saying this, the Web 2.0 model served its purpose, it got content management into every nook and cranny of Internet life. But at a cost.
We gave up control over the experience to companies whose incentives and interests conflict with ours. A necessary bargain when running a server is so complex and expensive.
New models for communication can develop, independent of the limits and needs of companies that run the Web 2.0 servers. I don't think Web 2.0 will go away, but a new net can take its place beside it. And that's all that's needed to boot up a new layer.