Ghostbusters: Afterlife will release next March, and features a reunion of the original cast from the 1984 film. Well, almost all of them. Rick Moranis barely acts anymore and is very particular about what roles he takes. He is on record saying he thinks it is "pointless" to return to Ghostbusters again. The other who won't be there hurts the most, and that is Harold Ramis. He passed away in 2014 and will be the only member of the four original Busters not in the film, though that doesn't mean Egon won't play a role in the movie, as teased by Bill Murray in an interview from The Ellen Show.
Ghostbusters: Afterlife Won't Be The Same
"We're missing two great people. We're missing Rick Moranis, and we're missing Harold Ramis," Murray said on Ellen over video chat. "And they're greatly missed for so many reasons. They were so much a part of the creation of it and the fun of it. But Harold is featured in the story of the movie, so it's going to be very interesting." This may be personal bias, but without Egon, none of this will feel right. Ramis was such an essential part of the team, not just on camera, and was my favorite Ghostbusters character. Him not being there took all the air out of the 2016 film for me as well, even though they paid him a lovely tribute.
I don't really think Moranis matters as much, what is important here is that the Fab Four are involved. Even then, who knows how much they will be or should be in the film as well. You want this new generation to build a connection to the new Ghostbusters like we all did back in the '80s. Hopefully, director Jason Reitman found the right balance.