As have all people in my generation, I saw the boom and bust of AOL, and it wouldn't surprise me at all for Facebook not merely to become uncool but also actively to lose money. It's been done before. I've been surprised, actually, at how well Facebook has scaled (I never thought its servers would be able to keep up with so many user actions in real time) and I've been pleasantly surprised too at how well I like to interact even with friends I regularly see in person on Facebook. But I could well believe that something shinier or newer could come along and draw away my friendship network as rapidly as it has been drawn away from other online services in the past.