A thought just came to mind less than an hour ago: the upcoming decade will see virtual world networks (within the "3D web") which are much less emphasizing of the "world" aspect (as in the "outside" environment of Second Life) and much more emphasizing of interconnected "rooms" (a bit like IMVU, but where the user creates one’s own persistent room in which to store models and widgets and simply invites or is invited to other rooms through hyperlinks embedded within the room).
This came to mind as I thought about how the World Wide Web had evolved in the 1990s and 2000s. In the ’90s, the emphasis was laid upon allowing people to create their own custom homepages, with a variety of template arrangements, on a number of ad-supported or user-paid webhosts (Geocities, Tripod, Angelfire, Freewebs, .Mac, FurNation, Furtopia). In the 2000s, most attention was paid to the rise of social networking sites which, while increasingly restricting the ability to arrange visual cues and templates within the page (i.e., from MySpace to Facebook), allowed users to post a larger variety of content by streamlining user publication of webpages.
So, if the variety of 3D virtual worlds continues to increase in the 2010s, I expect that the ability to create 3D spaces/rooms and post models into them will become further streamlined and automated, but the spaces will also become further boxed in and increasingly uncustomizable in the process.
This dynamic room publication will also allow users to make as many rooms in the 3D WWW as there are pages on the 2D WWW.