Man this news was a real kick in the teeth...
Concerning the sequel and it getting done or not, I wonder what Harold Ramis would want. I think he'd want the show to go on if possible.
Given the nature of the franchise, Egon could always appear in a sequel. Use old footage and make him look ghostly. They could even use it as the catalyst for the start of the movie, the funeral for their friend.
And I wouldn't mind seeing Egon slime Bill Murray's character.
Nice, and a scene with Egon sliming Peter would be worth the price of admission! I was thinking his (Egons) sudden death could have the guys considering disbanding in grief, but when a visit from Egons spirit brings information of a coming ghostly catastrophe they are reinvigorated into action.