I think the problem with his theory is that he is thinking of the desktop as a single entity. He thinks the _desktop_ should evolve to support streams better. That's a mistake.

The desktop is just a bunch of applications co-existing. Some programs have a document-centric interface because they deal with documents. Others have evolved an interface suited to the streams they deal with. MSN, IRC, RSS aggregators come to mind. I don't think there's more to it.

I agree that people are using streams more than before but I'm not sure of the implications of this fact.