It just doesn't have that fun feeling of knowing everyone anymore.
So are you going to quit your job when your company moves to a larger building and hires new employees? Are you going to drop out of school if you get moved to a class with people you don't know?
Go meet some new people. One of my favorite things about Blockland is that there is always more people to meet. I don't know all the people here, but I know a lot, and I'm always ready for new friends.