Huh, you're right. This movie is doomed to fail because we have four immensely brilliant comedic actors in their prime playing off of each other, not three. That extra actress needs to leave. I'll leave it up to you to pick which one but I'd be careful of Leslie Jones. She might snap you like a twig.
On a serious note, while the main three actors are a large part of why I enjoyed the original film, it's not the only reason. I enjoyed Ernie Hudson, I liked the supporting cast, it's a fucking great premise for a movie and the special effects are top-notch. All in all, this is about even with the original film in terms of everything. I feel no need to pre-judge a movie that hasn't even started principal photography yet.