I was just thinking and as mentioned, Sansa killing Ramsay would do nothing for her station at Winterfell. She has nowhere to go after that.
I"m just thinking that maybe she's gonna off Theon or possibly Myranda. Ramsay may be a b*stard and would kill off Myranda himself but she's the only one that seemed to make it out of his little fukk session knowing how to live so she must be something to him.
If she kills Theon, after all that work Ramsay put into breaking him down that'd really be just as big a blow. I don't get the feeling that he cares for either one of them, they're just his things and he's a brat. She'd take away one of his toys. It'd be extra because she knows that Theon didn't kill her brothers now which would just make it better for me somehow. What blowback that would cause I'm unsure but it seems the only way to go.
Either that or she's gonna forcefully abort that new Bolton baby and see how Ramsay feels about it.