It could just be another story in The Last of Us universe (Off-Topic)

by Korny , Dalton, Ga. US. Earth, Sol System, Monday, January 05, 2015, 19:55 (3405 days ago) @ Dan de Board

Ish, Tommy, Marlene, and Bill all have interesting stories that would be great to explore. Heck, the 20 years between the prologue and the main game would be great character development for Joel, Tommy, or Marlene...

Even the years after the game would be neat to explore with a new group, as maybe you could begin to push out and try to reclaim parts of the world all State of Decay style...

The universe is ripe, though I really hope they leave the main story as-is. Endings don't get more perfect than that.