I don't think they will die as there are enough 17 olds who have got enough time at their hands. However, it is true - social networking costs an awful lot of time. The question is, who will in the end have the biggest profit from it? Being a webmaster of a relatively small site you already don't know what to take care of first with all the new things that keep coming. You can't neglect all the "traditional" means of keeping your site(s) at reasonable search engine positions, and now you have to take care of all this social stuff, too. The only ones who can really afford it are the big companies, and those in the end will be the ones with the gain from social networking. As a "normal" webmaster you'll lose...