I think they should have let it grow as a franchise. I mean, an in-universe franchise. Nothing in the original two movies says the Ghostbusters must be those. Is only New York having problems with ghosts? I highly doubt it. I’d have loved to see movies about other people, especially non-scientists, that just bought equipment to enter the ghost-busting business.
But instead they waited to make a third one with the original cast. I haven’t seen the new movie, but they waited too long to do something like that. They should have done it earlier.