Personally, I think I might want to ride the Xtandi train for a little while longer, even if it only remains partially effective. (In the old days, some MOs and insurance coverages were known to use higher PSA number decision points up around 10.0 before prescribing it initially, or moving on to something else.)
I've also heard that on the "other side" of "resistance" to ADT, some doctors start to look more at the totality of things (scans, types of progression, sometimes genetic testing or markers, symptoms, etc.) instead of so much at absolute PSA numbers alone. There's probably less scientific "data" on these things in terms of clinical trial results or radiographic progression or time to skeletal related events or time to needing opioid pain relief or Overall Survival benefits. I'm no doctor, of course, but it seems to me that there is always a dynamic balance in decision-making between "starting too early or too late" or "quitting too early or too late". Individuals and individual doctors have their own comfort zones with balancing aggressive "up-front" treatment(s), with "buying time" at the margins of each treatment decision point, while living with an ultimately incurable disease.
If you live near or may be treated at MD Anderson in Texas, scouring these Clinical Trials & their details might lead you in some good directions, or help you to formulate new questions and new people to ask about
them.
/www.mdanderson.org/patients-family/search-results.html?q=prostate&searchType=clinical trials#filter|enrollment_status:openCharles