1. He could not Prove he is related to Tiber septim.
2. without the amulet of kings he cant prove he`s the next emperor.
3. I doubt the empire will name him emperor just because he is the dragonborn.
4. Final unless he can somehow convince the Concil that he is indeed the next emperor whitch I doubt they would, sadly the dragonborn will never become the emperor of Tamerial.
Thoughs are my reasons i dont think he will be Emperor, Though it would be cool to be proven wrong.
what do You guys think?