And just because it's happened in the past does not guarantee that it will happen again. People have been predicting the downfall of Facebook for years, but it keeps growing.
I assume the same will happen in my life for Facebook, Reddit, Twitter, etc. One day I will just stop.
^I use IRC for dev stuff now, but there was a good 5 years where it was no longer a part of my life. I was a gamer who played CS in the early 2000s.