Oh, don't you just love it when a series is wrapped up nicely? Like when we get to see Harry Potter's son going off to Hogwarts? Or Sam Gamgee putting in quality family time?
Sucks to be you.
Baggott's trilogy doesn't end neatly. It doesn't answer all the questions. And it certainly doesn't flash forward to some idyllic future where Pressia and El Capitan and Helmud are married and having babies. (We can't be the only ones that really want these two/three to end up together, right?)
At the very end of the book, our two heroes go their separate ways; Partridge stays inside the Dome with Iralene to either live out a fake life or die from an angry mob, while Pressia leaves the Dome with Lyda, El Capitan, Beckley, and her grandfather. Oh, and Bradwell's dead.
Here's our last look at Pressia and the world she lives in:
Her heart beats and beats and beats—each time like a detonation in her own chest—and every moment from here on out is a new world. (64.263)
We don't know what's going to happen to Pressia or El Capitan or Lyda. They're heading into a "new world," but really, it's still their old world — except the Dome is now crumbling to pieces. There's still ash falling from the sky, there's still pain and suffering, there are still fusings.
And now that the Dome has been destroyed (or is at least self-destructing), we're forced to wonder about what will become of the Pures. The future is unknown to us, and to her. There's no reunion with her father, who we know is still alive, and El Capitan and Helmud are still joined together. And what about Lyda's baby?
All we know is that the wretches will keep fighting for survival, just like they've always done.