The Ghostbusters II logo makes perfect sense in the movie. I already gave a rationale for it in another post. There also could be others.
I like the original logo, but to tell you the truth I like the GB2 logo better. If there is to be a GB3, of course they would need a new logo.
I agree with the posters who suggested the ghost be holding up 3 fingers instead of two. Makes sense to me.
But, since he is in a different position in the GB2 logo over the GB1 logo, he should perhaps be in yet another position for a GB3 logo.
Three fingers up, slightly different position.
The three-fingers up would symbolize the third GB movie outside the film, and inside the film would symbolize the “W” sign, as someone already mentioned.