Actually, the storyline for GFIV has already been sold to Paramount. The story line is that Vincent is actually a busboy in the restaurant where Michael killed Sollozzo where alot of wiseguys hung out. He used to overhear their stories, etc. and fantasized the entire Trilogy. As luck would have it one day he's cleaning off the table of a Paramount guy who's scouting locations for a new film and Vinnie starts talking to him and relating his fantasy. Paramount buys the rights and the rest is history!