Naughty Dog should work on an alternate ending where Ellie kills Abby and Ellie approaches Abby's kid (the person on the boat Abby was trying to flee with), explains to the kid why she killed Abby and then tells the kid that if they want revenge, they should come seek her.
Ellie is unable to kill the kid but she will defend herself if attacked. The cycle of vengeance will end with one of the two.
Dunno, just tossing ideas out there.
Well someone has been watching Kill Bill