I don't expect that everything will be all happy in Winterfell from now on. Everyone knows LF WILL try to turn Sansa against Jon, hell, he's trying since 6x05 when he said Jon was her half-brother
What I expect from Sansa is that she plays along with LF, pretends that she's following what he's saying, but in the end she backstab him.
Now, if she genuinely starts to believe in him and starts fighting with Jon... Then, there will be no defense for her.
But really, like I said right after Season 6 ended, I think we won't see Winterfell as much as we saw now, so if anything happens there, it will be quickly solved. I think Season 7 will focus on Dany conquering Westeros.