If Sonny had lived longer, he would have gone into drugs, and when Vito died, he would have been assassinated by Tessio who would have betrayed him. More importantly we would not have had the ending of the Godfather as we know it, nor a GF II nor, for better or worse, a GF III.
"Io sono stanco, sono imbigliato, and I wan't everyone here to know, there ain't gonna be no trouble from me..Don Corleone..Cicc' a port!"
