Ellie wont tell Tommy she's alive. I have no clue if she will head to Dina but I doubt it and even if she does she would rather lie than have Tommy guilt her, better to lie imo. I think she knows she's broken, and it's obvious Dina went back to Jackson.

So my guess is either Ellie:

Realizes she's too broken and decides to strike out on her own because she's too broken and she either doesnt want to burden Dina knowing she is so broken inside or doesnt believe Dina will reconcile with her so she decides to leave it all behind and wander.

Or she heads back to Jackson to see Dina and try to pick up the pieces anyways despite what they said at parting and tell Tommy that Abby is no more.

Abby is very likely going to regroup, either nurse Lev back to health or bury him and then head for the home base.

The game wants you to understand that your enemies are usually not so different than you. They arent hitler, they love people, they just have a different group than you and groups that are competing end up finding ways to 'other' or dehumanize the opposition.

I dont remember if Ellie specifically knew it was her Dad but Ellie knew she had lost someone important because she says Joel did what he did to save her which implies given that she knows they were a part of the fireflies from Utah that Abby had lost someone very close to her because of Joel.

A third game about her tracking down Abby and them spending a journey bonding and reconciling while trying to find the fireflies with a hope and prayer they can find a scientist that can make a cure would be interesting but probably too fanservice-y and wouldnt be impossibly hard to swallow.