The current generation of kids do, just as the current generation of parents and grand parents do. This doesn't seem to me like a mix that will survive long - FB will eventually split into an adult only thing with the following generation gravitating to something else, and thus will eventually whither and die.
I think the article is generally right - a large group will eventually split into many groups, be it by age, common interests or as a reaction to a lack of privacy and against the 'establishment' in general.
Lo! Men have become the tool of their tools. -- Henry David Thoreau