yeah i think the effects of HRT are partially reversible in the sense that some effects go back to how they were previously when you stop taking the hormones. stuff like skin getting coarse again and body hair growth intensifying when you end m-t-f pills. also fat redistribution. but the reverse is only partial, i.e. it doesn't go back quite as much as you started out with.
like when you edit the shape of foam, and then stop, it partially bounces back, but only partially, it's still visible that some pressure was applied to it. :)