There are three flaws with your theory. #1. Mib 2 cost 97 million. GB 3 (accourding to Aykroyd) will coast around 120 million. Thats 23 million more. That ain't chump change. #2. Mib was made in 1997(or 1998, i forget). GB 2 was made in 1989. So awareness for mib is naturally higher then ghostbusters because the last GB movie was mad 13 years ago while the last mib was only made 5 years ago(even though MIB is a huge rip-off of GB IMHO). #3. MIB really only needed 2 major people to come back. Both agreed. GB needs at LEAST 4 major characters to come back, and one has repeatedly said no(Bill you Suck). Now I am not saying GB 3 will never be made, its just doubtful. I hope I am wrong though.