The Others
Sansa Stark
Sansa ruling the North seems a given. Her sitting the throne does not, which is why it is totally possible. At this point for anyone to assume the throne, we have to assume both Jon and Dani are dead. As long as one of those two lives, the throne is theirs.
However, if they should both fall what happens then? Sansa is perhaps the best choice past the first two, maybe even including the first two. As i stated in my wolf article, Sansa quit being Sansa Stark about the time Lady died. Her real name should either be Sansa Lannister or Sansa Baelish.
Her entire life during this show has been learning at the feet of the masters of manipulation in both Cersei and Littlefinger. Sansa possesses the cunning, the ruthlessness and political know-how to effectively run a nation. More than Dani, and way more than Jon.
I would like to say there’s a way Sansa could rule Westeros, while Jon stays in the North, but the blood claim is in Jon, not Sansa. Could she be hand of the king? Again, she has the courtly wisdom, but I see Sansa ruling the North in every scenario that does not lead to the Iron Throne.
Tyrion Lannister
I think the only other person who could sit the Iron Throne would be Tyrion Lannister. He has the wisdom and heart. His past history demonstrates how well he could do. His actions remained correct. The problem was he had an insane nephew and controlling, hateful sister over his shoulder. He received all the blame when he should have garnered all the credit.
I think we have seen he has zero talent for military planning. Cersei outmaneuvered him at every turn because he simply lacks the ruthlessness needed. Pretty sure at this point, however, all of Westeros will be plenty sick of war.
Tyrion’s biggest detriment will be his name – Lannister. The people will not wish to suffer under a name that abused and starved them for these past many years.
Here Sits An Empty Chair
Only four people may sit the throne, but there is a fifth option. In the even t Dani and Jon fall, does Sansa really give a shit about the rest of the continent? Her heart lies in the North. No one will follow a Lannister and I doubt Tyrion would want to return to the lifestyle that ruined his life.
If no true leader exists that the seven kingdoms can unite behind and there is no longer a solid blood claim to the throne. It would not surprise me if the the seven kingdoms remain exactly that – the seven kingdoms. Westeros would resemble modern day Europe.