Who will be the last person on the show to rule Westeros?
I phrased the question this way in order to allow for the possibility that no one rules at the end.
Coffin-Key-Man-Paths-Tower
My first thought seeing this is that Bran will rule. Coffin-Tower reflects his fall from the tower in the first episode. His powers also give him certainty of vision along all the roads of Westeros.
Another possibility might be: "End of certainty for the man who chooses to stay above the fray" The fray, I think, would be political rather than military, someone who hasn't sought the throne. We saw Davos's certainty of the world shaken vis a vis the Lord of Light and the last acts of the Red Priestess. He's never sought his own power.
A final thought: The first "person" card I came across was the child. Could the show end with a new generation of royalty? Either Gendry or, perhaps the show ends with a pregnancy of some sort.