1. You become the reincarnation of Tiber Septim or Martin Septim
2. Martin or Tiber could return and fight off the Akaviri. (Considering what Ocato said at the end of Oblivion)
It would be cool if Martin could return, as I thought he was the coolest character in Oblivion, although it might not fill in with the Mede dynasty in the Infernal City, unless they were in parallel dimensions or something.
