From a film treatment for Ghostbusters III by John Landis’ son Max:
Ray, in the meantime, has made his way back to the firehouse, to find it destroyed. He walks through the rubble of his life’s work, utterly broken. All those moments. Slimer in the ballroom. The TV commercials. The fame. The statue of liberty. He was a hero. They were all heroes. He picks up a photo of himself, Winston, Egon and Venkman, and tries to call Venkman.
We cut to Venkman who’s on the beach on a tropical island with his grandkids. [Venkman] forwards the call.
This would be a throwaway cameo for Bill Murray, who gave the original Ghostbusters its wise-cracking soul. Murray famously passed on Dan Aykroyd’s own treatment. Who can blame him, given the Blues Brothers 2000 train wreck?
(Landis’ treatment isn’t great, either; it reeks of nostalgia and features a convoluted subplot about failed Ghostbusters franchises all across America.)