facebook just a fashion?

Is facebook is just a fashion that going to make us smile when we think about it next year?
I was asking my self this question in the last couple of days (while playing with facebook)
My answer is... i have to believe that some of it will vanish... (all the useless applications)
and some of it will stay for good.
I think that social network (specially facebook) is actually Instant messaging 2.0 it's a new way to communicate.
so it's going to be an exciting months to see whats going on with facebook.
is it going to be the next web OS and IM platform or just another web 2.0 over rated site.
Navot