I made my account around Fall 2007 as a high school student. It completely changed how I did things and I'm still a happy user all these years later (and still have access to my poorly-written high school papers!).
People were sounding the same alarm in the '90s with AOL. History has shown us that, at some point, a leaner, more innovative company will surpass Facebook.
Well they were kinda right. AOL was merely an early iteration of what we have now. Maybe another company will surpass FB but I am pretty sure from iteration to iteration it will be harder and harder to replace an incumbent since each round's winner will be more powerful than the previous one.
AOL, for instance, was mostly an American thing. FB, otoh, has global power.
Congrats!