Been on HRT for quite a few years already but sometimes worry that HRT will no longer be available in 10-20 years from now.

Stem cell technology is developing. So once it's possible to give menopausal women and post-op trans women lab grown ovaries, where will the rest of us source our HRT from? Those of us who are non-op. Will we still have the option of getting HRT supplies at our local pharmacies? Will it's access be severely restricted?
Will it be affordable still?

Things that I find myself seriously worrying about on a daily basis.

Where will I get my meds from in X years from now.

I hate being dependent on external medication.

I know you say your non-op, is an orchiectomy out of the table for you as well? Having that surgery alleviates this feeling a lot. One of the main reasons I had it done.

It is likely that most of the world won't be able to afford the new technology, so the older meds will still be available as long as someone can profit from making and selling them.

For sure what Maid Marion said. I wouldn't spend too much time worrying on this one,  there are hrt supply issues today that are probably a more pressing concern.  Even if and when we can master stem cell tech and the cascade of developmental signaling at the level of generating functional ovaries that gain FDA approval, there will still be plenty of cases where simply taking hrt is a much lower risk proposition than undergoing surgery for a variety of conditions and so it would likely remain a very viable methodology in healthcare.