You know, unfortunately I have never had the chance to meet anybody that had the ETS clamping reversed. I have heard that there are ways to reverse it, but never actually met or spoke with anybody that had it done.
I would imagine that once you get it reversed, the sweating would likely resume how it was before. But again, I don't know. I'm only speculating.
The best thing for you to do, my friend, is to keep researching, talk to the surgeon, and maybe get a second surgeon's opinion as well. Good luck.