He Could've Done More.

That, he could've played more characters, whether James Caan (1940-2022) himself liked it or not, aside from one part hallmarked his entire career, as Santino 'Sonny' Corleone, of "The Godfather (1972)".

However his presence over the other films were unique, and impressive, very different from one another, the best of all, opposite Oscar-winning Kathy Bates in "Misery (1990)", or opposite of Barbara Streisand in "Funny Lady (1975)".

The numbers of films, could be compared to Al Pacino, Robert De Niro, and Brando's, that he could've done more, and as good.  In our memory, as dedicated as the 50th anniversary year of "The Godfather".