So, there has been much debate on whether Second Life has a sustainable future. Marc Sirkin has weighed in on the subject, as has Clay Shirkey , and true, the sheer numbers may not be truly telling the whole story. It took me about 2 years to take it seriously myself, but now we are finally moving forward. Here's where I think the future lies for this: the integration between web site and deep link into second life. For now, the barrier is too great - you need to download a file, create your avatar, and figure out how to navigate. But once SL becomes more ubiquitous, that transition could be almost seemless.
Imagine for instance, that you are shopping for a house. You look on one of the real estate sites but want to take a closer look. You are teleported into the house itself - you can walk upstairs check out the closets - everything. Much less time and effort than making an appt and physically showing up. You don't have to see ugly furniture either!
That's where the value is for me, we just have to wait for the usability to catch up. It's a bit too techy for the average user, and I personally have felt the bugs each time I go in, but whether it is Second Life or some other virtual world - or tool, we'll be seeing more of it.