I’m 69 and bought my first road bike only 10 years ago. I’ve made some power/FTP gains but am transitioning now from the SS/Threshold focus to a polarized approach with 80% endurance and 20% Vo2Max, based on the advice of Joe Friel and Stephen Seiler. My weekly goal is 100 miles. I think your original question is as much philosophical as it is technical. What are your goals for your cycling and other exercise? What is your weekly mileage? I’m taking a more holistic approach than in the past, knowing that the marginal gains from doing more than 100 miles or 8-ish hours weekly are not really worth the additional fatigue and potential overuse injuries that could occur. For cardiovascular and cognitive health, I likely get very little additional benefit by doing 100, rather than 80, miles a week. My goals include longevity, being active until I keel over, camaraderie, the sheer joy of cycling, and still being able to have a goal to improve at a sport, while most of our peers are sitting on their duffs.
As we age, weight training is vital for overall health and stability as much (or more) than it is for cycling prowess. Frankly, it’s not nearly as much fun as riding my bike, but the long term return on investment is much better than spending those two hours in the gym v. on the bike.
I share your desire that TR should scrape all of its data for master cyclists and provide us some guidance, but doubt it will happen. The only nugget I’ve heard is Nate’s statement on the podcast that, based on TR’s data, an older cyclist should never go above FTP during an event if he wants to get the best overall time because this age group simply can’t recover from those hard intervals like younger cyclists can. (Still not sure how I’m supposed to climb hills at FTP or less 
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As Phil Cavell says in his excellent book “Midlife Cyclist,” we are part of the first generation who has actively continued an aerobic sport in our 50’s, 60’s, 70’s, and beyond. Someone really should be doing a longitudinal study of our group.
The number of over 60 cyclists is certainly growing and quite a few of them are on TR. I started a thread for over 60 TR subscribers two years ago that stays fairly active. Who's over 60 y/o and using TR?