Maybe an approximate mileage or a range is the best way to go...

Actually, it's a great idea, but it would take a significant amount of solid data to make it worthwhile. In the aerospace biz we employ thousands of people who take real service life data on almost every high-value part, and using things like Weibull analysis, they prepare reliabilty analyses which predict when the parts need to be swapped out. In the aggregate, such an analysis would consider the 100K blown-up engine as well as the more typical 250-400K lifetimes, it would be 'blind' to whether the car was in taxi service or driven by Grandma on Sundays. Failure modes are typically categorized as 'infant mortality', 'wear-out', or 'accident/random failure'.

But for us mere mortals, we tune into Brickboard and get empirical as well as anecdotal information so we know what to prepare for!

Nahh. Life is more interesting and educational with surprises. I just go along until something requires my attention.

That's a great idea, but experience varies all across the board. The only items you have reasonable predictive powers over are the cooling system parts: radiator, heater water valve, hoses, and thermostat. They all last a maximum of eight to ten years (depending on use and temperature) and most start failing like clockwork. Regrettably, the failures are catastrophic. So I replace these whether they "need it or not." All else is so unpredictable that I listen or look for symptoms and then act accordingly.

While that's a great idea it's going to be kinda hard to do.
Ex., there was a guy in B.C. who a 78 240 with 750,000 miles and no major work done, just basic maintenance.
I've got a 83 245, 350,000 km, and it's on it's 2nd engine(the present engine had the same milage on it as the previous so really it's lasted 350000 km), 2nd rear axle, original blower motor (it's been making noise on and off for 4 yrs but it still blows) original steering rack.
It all comes down to use and abuse, the B.C. guy was all country highway miles and he was tip top in maintenance. I've seen 240 in scrap yards with 100,000 that have already blown an engine. My advice is to do your maintenace, if you're into it you will notice different components that are starting to wear out and this will give you a window of opportunity to replace badly worn components before failure.
I used to have a tendency to repair things before they broke, but then after fixing one thing a previously undetected something would break and I would find that I had been fixing the car all week. This is not why I use volvos. Also the componenet failures I have had all gave me plenty of warning signs or in the case of engine mounts, allowed me to limp home for repairs.

Patrick, '68 220, '83 245.