Over the years with other MTFs in my support group they did the slow change until it got to the point that they were only fooling themselves that they were still passing as males. Making it official was not a big thing. Old, bald and ugly types like me can't do subtle. If/when I come out it will be more like an atomic bomb
As one brilliant engineer to another I can absolutely assure you that no matter what official "Policies" there are, if management wants you out, you're out. Even if you are the the one brilliant one among two or maybe three other engineers there. I've seen it happen to others and eventually to myself. Having been in upper management I've seen/had to do it. These days only a PHB will be stupid enough to say, "Sorry errr Ms Jones, we need to dump your ass because you are one of those transformer types and I, I mean we can't have that here at Dewy, Screwem, and Howe. Please, don't beg, this comes from the top, and is all here in writing"