Given the connection to FB (development team) and the visual nature of the site, I'd say it has a good chance of persisting into the future. Now if they can just handle the legal issues (copyright, etc.).
Pinterest has found a niche and offered something a bit different from other sites. Pinterest is also attracting a larger following of female members from what I've been reading, so their demographic is a bit different as well. I'd like to see them continue to grow.