I used to live in Chicago and have a very strong network there. I actually grew my network in Chicago while not living there because I continued to work on good

I used to live in Chicago and have a very strong network there. I actually grew my network in Chicago while not living there because I continued to work on good things and by being active on the internet. I expect that the same thing will happen with my SF network as I move back to Chicago. It all depends on how you interact with those people. If they are actually strong connections, which mine are, then you will not lose them by being in another city. They will also want to stay connected to you even though you are gone.