Yes, I think the wolf share program is out there. However, we have never had the rule that two wargs can't share the same creature, right?? Good point that there is often bonding involved, however, some examples show that there is not, or that there can be antipathy (Varamyr). I don't think that seeing that idea as improbable is negative.
If Sansa does have many Tully traits, she very much might have a streak of steel and vengefulness, like Catelyn. Hoster and the Black Fish are no pushovers. Edmure...well, we'll see.
Hodor accidentally killing Jojen is possible. Especially if you consider Wun Wun's actions. Hodor's death might change things for Bran...It would also be tragic.
It could be important to the story that Hodor was scared about being warged into, and will adjust to it. I'm not saying I don't like gentle Hodor as a character, but I do think his invention was probably as a "steed" for Bran. That is not how real life works, (and how we may believe passionately in certain unalienable rights) the but in writing, I suppose, every character is also a vehicle to some extent, and they are not created equally. I suppose the idea of Bran/Hodor swinging a Claymore is too tempting an image to give up on as yet. I guess I don't believe that Bran would just snatch Hodor's body, permanently, either.
I don't know what will happen with Meera. But her fate does seem like a loose end now. I never considered marriage with Bran! If Meera decided leave the cave in order to fulfill some task, I don't think Bran could stop her. In fact, Bran might want to go and warn, help or save someone that he loves. Someone also needs to tell the people south of the wall what has become of Bran and the tree network.