Well, first of all, I was glad to see that Joel was alive at the beginning and conclusion of The Last of Us 1.7, fulfilling what I said in my review of 1.6 last week, that if you don't see a character's head cut off or blown to bits, there's always a chance that she or he survived.
Now all of that took maybe a minute to show, and The Last of Us devotes the whole rest of the episode to another nearly standalone story, this time of Ellie and her best-friend Riley, whom she also has a crush on, back in Boston, after the fungus apocalypse, before she ever met Joel. This story within a story was woven in so well, I didn't even quite realize that Ellie was back in time and in Boston until Riley said something about needing to leave Boston the next day. And then everything, including Ellie's mention a little earlier of a time machine (a nice meta-touch), fell into place.
So, does this now mean that Joel and Ellie are permanent characters on this series, or at least for this first season of this series? Perhaps not, but I think there's a chance that they will indeed endure. And I think that's a good thing. You can't make everyone expendable in a story. Or maybe you can, but I think stories are always enhanced by having some permanence, some continuity, of characters.
This season will end after two more episodes. And HBO has already called for a second season. I'm hoping we'll see Joel in all of that, and more. In the meantime, it was good to see Ellie's first love tonight, and in what circumstances she first got bitten by the infected. Riley presumably didn't survive. But her very wise advice that the two shouldn't take their lives, and instead live every moment they had left to the fullest, not only made everything we've seen of Ellie in this first season possible, but is very good advice for all of us on the other side of the screen
See also The Last of Us 1.1-1.2: The Fungus Among Us ... 1.3: Bill and Frank ... 1.4: Gun and Pun ... 1.5: Tunnels ... 1.6: Joel
I talk about The Last of Us, beginning at 40mins 40secs