Sorry for the confusion -- I assumed that, absent the contract dispute with Richard Castellano, the storyline with Frankie Five Angles would have involved Clemenza instead and that he would have killed himself in the bathtub.

I presume that, if Castellano had remained in the movie, the final scene at the kitchen table would have also included Clemenza. It makes more sense with Clemenza, especially given the flashback scenes in GF II which make no mention of Frankie yet feature Clemenza (as well as Tessio -- who also appears in the final scene). It also would add to Michael losing "his family"