There are treatments written by board members about the possible GodfatherIV, you should read some of them. Why not try making your own?

That doesn't sound that bad. But.. Vincent is a two dimensional character, who's not intriguing enough to watch, and there's is definatly no way Garcia who's a bit better then a mediocre actor to carry a movie of that magnitude on his back. Plus: there is nothing else to tell about Micheal, that would be at least a bit pertinent to The Godfather story. Immobiliare would never fall. Specially since the Vatican board only owns 25% of it. And it's one of the largest conglomerates in the world. Micheal had control of the board. Vincent never did. The control board of Immobiliare was already killed in Part III. And Micheal died already, which probably meant the deal did so as well with him or even before his death. Remember the excitement he showed when the news that the pope had given him control of the board were delivered to him?

He would never give Vincent such control. The pope would have to approve of Vincent as well if he Micheal did, and if Vincent did receive such power.. How could he be in debt if he controlled the board?- Micheal seems to cut all ties with everyone after Mary's death. For the information known Vincent could even be dead by the time Micheal is show. The possibilities are endless.

Guineapig.