I'm so sorry—I didn't see your post!
There's no way to know if a thymectomy will help or not. Since many of the thymectomy patients that they do studies on are on immunosuppressants, it's not easy to tell what it was that put them into remission.
It's such a personal choice. And it really is a crap shoot as to whether it will help or not.
Is she doing okay on the meds she's on?
Surgery also has risks, such as ticking the immune system off even more. Some studies show that you can get another AI after body stresses such as surgery, infection, pregnancy/birth, etc.
I wish there were better studies on thymectomy. I read some of the initial ones that were done ions ago and the statistics are basically the same as they are now.
Whatever she decides, I hope it goes well for her.

Annie