I think (and hope) that it's never too late. I'm in my early 60s, and after a lifetime of repressing , deflecting, and otherwise hiding, I hit some really black days recently. This stuff really backs up in the psychic plumbing. I finally got the courage to actually make an appointment with a therapist in our HMO next week. I wish I'd done this 40 years ago, but with today's treatments. (Not electroconvulsive therapy or faradic aversion treatment! Eep!)
Oh, is he in for a wild ride. I very strongly suspect the depression, anxiety, etc is all coming from gender dysphoria, and am hoping to get a referral to the right team for treatment. (The HMO has a specialized team for these sorts of issues.)
I haven't come out to anyone yet, and will try to get some good guidance before I do anything that might blow up my life.