I don't doubt that some were ready to leave. Not an uncommon thing when TV show breaks but would anyone have left? I really doubt that. HBO would have given them the money necessary to lock them into contracts for however long it was decided to go.
The problem with Bran being King deals with how rushed it was. You have no idea why the characters on that council would be ok with him or even if know anything about his powers. You don't know why Yara and "The new Prince or Dorne"
don't follow Sansa into independence. They just all kind of followed the guy in chains. A guy at least some of them probably wouldn't think too highly of. If that book scene at the end was taken seriously instead of the joke Tyrion would be a villain in it. He was never liked, most would think he killed Joffrey, and most would think he led the Mad Queen to murder everyone.
Problem with too many seasons is Dany. Once she has the army and the dragons its hard for the audience to not be annoyed at her not just going and taking Kings Landing. Another shorten season could have been the best situation. Could have had this season focus on the Night King which would have made it less of a letdown and then next season Kings Landing allowing that to have more time.