in one of the other threads I posted that GF4 can start with Michael's funeral, with Vincent in a prominent position (like Mike on his dad's funeral) and then cutting to a 1920's scene, with the texts on screen saying: VINCENT MANCINI, 1997 and then HIS FATHER, SANTINO CORLEONE, 19.... and so on.

Also, the 1980's and 1990's story, if there would be one (based around Don Vincent) can include Michael.