this is a really good question. I don't know. I think the next adopters would completely depend on the first killer app based on bitcoin. Whatever area that killer app is in, that's the people it'll bring in.
If we take all internet users as a target market for Bitcoin, we are in the early adopter stage ,this same type of discussion was happening about facebook/myspace when when social media began. "Why would I want this?" and see now as we are