Hm…but there was that 20 year or so gap between Star Wars Episodes 1-3 and Episodes 4-6. But that's because Lucas said he didn't have the money or equipment to do what he wanted to do…oh well.
Personally, I don't really mind a GB3 film. BUT, everyone else that I talk to (that I know in person or online) seems to say they hated ghostbusters, and don't want to see another movie. Seems like most of the public (besides some of us at this message board) doesn't want another film of GB. I do though! Bring it on!