Good question. But don’t expect a concrete answer.
Weinberger’s reply is that we don’t know and really can’t know.
In fact, it’s likely we’ll never get to something that can be tagged with the next increment like software.
Web 2.0 also makes it less likely that a single change will sweep the entire Net, for Web 2.0 makes it easier to diversify the Web’s offerings. So Web 2.0 may also spell the end of giving the Web point revision numbers.
With any luck he’s right and we can figure out a name for all this stuff that makes more sense to people outside this echo chamber.