Do a lot of TS go back to being guys when they get older?  Unless they got cosmetic surgery all they'd have to do is stop taking the hormones, right?

although there is probably at least one reversion, my guess (and it's only a guess) is that they do not revert.  They spend years being women, many have surgeries (implants), and most take hormones and have laser hair removal.  It takes a lot of work to turn John Doe into Jane Lovely... more than makeup and a wig!