Look at it this way:
If you go on HRT, and start losing your hair, then maybe it was meant to be.
I've found that a lot of guys over 35 (and I am 36) are overly concerned with their hair...dying it, styling it, whatever, but they are so set in their ways they still wear it in some lame style from their 20s. My buddies in their early 30s are doing ok, my buddies in their 40s seem to have either some preoccupation with metrosexualism, or other weird self-image delusion.
I'm bald as hell, myself, and don't really care.
Other than that, propecia, nizoral, and minoxidil probably will stave any HRT related hair loss off.
Dan John once told me that overhead squats will stop you from going bald, and keep your jimmy working like CRAZY, but not if you follow them up with curls or triceps kickbacks.