Im with the guys saying Dina is the antagonist. She may not even be the primary antagonist, but she's got to be the enemy. In the recent gameplay, Ellie sarcastically asks Dina if she knows how she'll die. Dina sarcastically remarks that yes, Ellie will kill her. That was foreshadowing, albeit tongue in cheek. It's got to be Joel she's avenging. Not only narratively, but for the players investment.
The big theme has been repeatedly touted as revenge. If you played the OG, you're not going to care about Dina like you would Joel. The savage killing sprees wouldn't be nearly as cathartic and personal if it was all over a character you've known for roughly all of 45 minutes. I think Joel dies, and I think he dies in brutal fashion. I fully expect ND to gut punch everyone. The first half of 2020 is loaded.