A brief timeline:
I’m sad to report that Aykroyd has decided to move on and make the unnecessary sequel without Murray. What did you do, Ray?! WHAT DID YOU DO?
“I can tell you he won’t be involved. … It’s sad but we‘re passing it on to a new generation. Ghostbusters 3 can be a successful movie without Bill. My preference would be to have him involved but at this point he doesn’t seem to be coming and we have to move on. It’s time to make the third one.”