There are a few things that make it likely, in my opinion. There are the
of course, and the males might be interested in the "new flavour". And an instinct-run thrall would be considered easy. There are less unattached males than females, but adultery isn't uncommon among weres. And even though she's mated, I don't think Peter is going to have an easy time defensing his rights, if he even tries.
All in all, I think the only real protection Sarah has except for her own power is the danger to the secret she poses. The whole situation is too dangerous to mess with, and Jack would have warned the rest of the pack off.
Still, even with her current physique, I wouldn't be surprised if someone in the pack starts thinking with the wrong head the coming full moon and tries to score with Sarah. Noah already did so, in fact, although he doesn't seen to realize how dangerous the situation is.
