Safe to say I don't know the validity to these claims and even then writers of the article have not 100% confirmed the legitimacy of what they read, but it's an interesting read. The following link claims to have read the most recent draft of GB3 before reboot fever hit. I really like it and what it describes happening to the original team at the end. Heck, I'm ok with the idea of the reboot, but this makes me sad as to what could have been. And the role of Venkman in the story is, in my opinion, pretty brilliant considering how he feels about another Ghostbusters.
Take a look:
http://bloody-disgusting.com/news/3321478/weve-read-the-ghostbusters-3-script/
The Ghostbusters Inc. described seems to be what Feig was wanting to avoid...a world where ghosts are commonplace.