Unless they had Hagen die of cancer, get assassinated, or go against the family, Hagen's role would have been a lot like Harrison's.

Sure, there would have been more to it, but nort by much.

However, I believe they would have done something with the character. Mike and Tom's storylines were dangling out there at the end of Part II and it would have needed to be tied up in Part III.

And if Paramount needed a Part III so freaking bad, why didn't they just give Duvall what he was asking? I mean come on, he was in Part I for crying out loud!!!

Shame on you Paramount, shame on you!!!