Still like the idea of him being at least a bit autonomous, with a plan. On the idea of Bran, I wonder if he could control the NK in the end, even temporarily, for enough time for them to kill the NK - effectively killing them both. Or killing Bran in the NK's body and having the NK trapped in a cripple. And then whoever kills "Bran" is labelled a traitor and killed.
Hopefully he will talk. I will be surprised if he doesn't. He MUST have a plan, hence why he has let people live or get across to the other side before making them wights, for example. I'm thinking he was created to create defend Westeros from destruction and that is still his goal - destroy those who threaten Westeros, but that doesn't mean everyone. He will kill who he thinks is bad/causing destruction and will leave people behind to try and make a better world. If they fail, he will return. That is just my thought.