Peter Spiro, Marty Lederman, Dave Hoffman and others are wondering about this question over at Opinio Juris. I think I'll stick with the prediction I made in October 2005:

It's hard to predict these things, of course, but I would suggest a fourth future [for law blogging]: A continued increase in the overall amount of law blogging until we reach a natural equilibirum, and then a roughly constant amount of blogging with frequent turnover among active law bloggers. Here's my thinking. Right now law blogs are pretty new, and the number of law bloggers is increasing. But it's much easier to start a blog than to keep it up. A typical post might take an hour or so to research, write, and edit. And the better and more thoughtful the post, the more time it takes. Only so many people are willing to put in those hours on a regular basis, and members of that twisted elite group presumably will change over time, too.