There is a limited spectrum of masculinity for males (pansies) and a limited spectrum of femininity for females (tomboys), but boys will be boys and girls will be girls. (Homosexuality, though related, is a different matter for a different time.)
The knee-jerk response of saying Transgenderism is just “Sirus” and/or “Lo Sakifu”, “Lo Sashchis”, “Lo Yilbash”, etc. and mental disorder seems solid. Those who try to uproot the simple view of things with their customarily shoddy vagueness of: “Yitzchak had a female soul until the Akeidah according to Kabbalah”, or saying Dinah was more masculine by going out and Yosef feminine for improving his looks at 17 because they were exchanged in the womb according to the Targum, are saying… What, exactly?
There are maybe 3 Teshuvos on sex-change surgery’s Halachic effect. And do they have “meat”? If you’re not extracting serious proofs for determining novel cases from the sea of non-Aggadic Talmud Bavli, you aren’t adding value.
Bottom line? Until and unless Rabbi Brand or someone of his stature looks into it anew, it’s a non-issue.