Yeah but who would take their motor apart and only change the rings? Taking the motor apart should always blossom into a full rebuild as long as the motor is out and apart.
I've seen enough (driven/owned) enough high milage oilburning cars to not worry about ring wear. It's never been an issue.
My current 1991 mustang went through it's entire oilpan full of synth oil going from biddeford ME to acadia park (300 miles? something like that) and the car stalled when I got off the highway. I checked and there was zero oil left. Barely a drop at the bottom of the dipstick.
The SAME un-rebuilt engine now goes 2000 miles before losing a quart or less and the only difference is me swithcing to heavier non synthetic oil (I scraped the carbon off the piston tops and made em gleam when putting my 40-p's on, thus removing the detonation issues that carboned pistons cause and buying myself a lot of time). I could bandaid this indefinatley. Ring wear rates decrease as mileage increases since the tolerances increase. The main and cam bearings will wear out but the ring wear rates decrease after a while since there is less interference from thinner rings and larger bores. There is more wear going from 0-100k then 100k to 200k.
Unless you're trying to build a 10 second car, you can get away with a lot.