The universe is huge and Thor has plenty of "friends" we haven't even seen yet, so glad to hear it. Plus as a character it fits that he would be around forever.

I hope they have the self-control to save Thor and Loki reuniting for this, instead of breezing past it in Doomsday.

I really have no idea how they'll handle it in Doomsday. While we and the greater universe know where Loki ended up, you can't assume the average viewer has seen the Loki series. I'm not even sure you can assume the average viewer is familiar with the TVA, although you can introduce them pretty easily.

But also Loki and his current position is tied to the entire idea of the multiverse. You can't conclude the multiverse saga and not include Loki in a major role.

My best guess is have Thor follow some series of odd clues. Have those clues remind and flashback to Loki. Have Thor remind the viewer that Loki escaped in Endgame. Discover some magic thing, see Loki for a moment, then ignore that during secret wars(?) and then post secret wars be confident that Loki is out there in the universe.