Well, the whole elves living a very long time is associated with elves in all cultures, which is really just Norse culture, in other lands they are more associated with Fay or Faeries, which also exisit in TES, we just haven't seen them yet. I think that they just reproduce less because of their long lives. I don't know why, but if you lived for a thousand years and were a human, you would basically be Walder Frey times one hundred, but if you're an elf, not neceserally any really. Elves don't seem to mate as much it seems.
I think that the Dragonborn has some kind of destiny, that will be hinted at in the next game. Nerevarine went to Akavir, Hero of Kvatch because Sheogorath, other two died or were presumed dead, or at least the Agent of the Blades was. Now, the Dragonborn does become Miraak's replacement, and they are invited to Sovngarde, and they are called Hjalti by the ghost of Old Hroldan. It seems to me that they have some connection to Talos, possibly replacing the Aspect of Ysmir, one of the three beings that comprise Talos the deity, along with Tiber and Zurin. I do like the idea of them travelign the Sea of Ghosts and eventually becoming ruler of some island, enclosed by ice and snow. Could be a refrence to Issgard. I think they should put nods in there for some mods.
So, after Skyrim, it would be mentioned that they ended the conflcit in Skyrim, Emprie collapses either way. They mention things like traveling with a vamprie woman, dealings with werewolves and vampires, travelign so Solstheim, slaying Alduin the World-Eater, could be mentioned by the Psijic Order, and eventually they did the traveling and becoming ruler by their own hand thing, possibly ascending atfer that.