Five minutes in my kitchen brainstorming out loud led me to this:
So Bill Murray isn't interested. Let Venkman have drifted away from the other three. He can have a glorified cameo, or just be mentioned by the others. Have Egon have died recently, since Harold has, and maybe they saw him at the funeral and it was awkward because they were all still into that and he just wants to move on in his life with Dana. So Winston and Ray realize they need to get some new blood in. The world has changed, though. Parapsychology is more mainstream. They wouldn't have gotten evicted from the campus these days for what they were doing -- they'd be having regular classes and lectures on it. So maybe what the Ghostbusters are now is guys who work with paranormal investigation teams and get called in when a haunting is persistent and won't yield to cleansing rituals or trying to communicate with the deceased or whatever. And the tech has gotten better and more streamlined and amplified and miniaturized over the last couple decades, too. Like the whole thing is now a sort of large bullpup handheld unit*. Something happens. Hijinks ensue.
[
*This actually dates back my post-high school role-playing gaming with friends. Since Marvel published the Real Ghostbusters comic, we treated it as set in the Marvel Universe for out Marvel Super-Heroes stuff. S.H.I.E.L.D. had had enough run-ins with supernatural threats that they nationalized the Ghostbusters, Stark got his hands on the proton packs and made them faster, stronger, better... and we the players were part of a newly-formed Avengers Department 666. 
]
So for this to be going in the direction it is is utterly unjustified. That was a couple minutes of thinking out loud. These are supposed to be professional writers, for chrissake.
--Jonah
