Took me nearly 10 years but I finally hit 500k miles on the way back from Vintage this May. Not a "lot" has changed as far as I remember. Same parts car engine, but the clutch blew up at some point and required changing. All the little springs in the disc fell to the ground when I slid the bell housing back. Still running off the old two fuel pump setup, not original by any stretch but I've had enough spares to keep it functioning, no idea which I've actually changed or how many times over the years. AC has given up but there's still a small spritz when I depress the schrader and all the other components are present and accounted for so I may gamble on a few cans of R12 to see if it comes back around. I also did tie rods for sure in the last 100k and UCAs probably, (bushings at minimum), and then the LCAs just this spring, but with some new steering components and an adjustment the original steering box is still hanging in there.
The passenger side front B8 gave out so I replaced the pair with a set from vviking within the last couple years. I'm unsure of how many sets of brake pads but I bet it was only one. I replaced the rotors and pads right before Vintage this past May. Oh, and the exhaust had finally become a hazard but I got over 20 years out of the Stahl and Supersprint catback. They were replaced with a full Supersprint setup at the same time as the brakes. That project was nearly 2 years in the making, it had been sitting on jackstands in the garage since barely making it home from Vintage in 2022. I had to borrow a tire, thanks Cactus, and get some replacement fuel line, thanks Fikrit, but she made it. I'm going to have to go for classic plates now too since I binned the Magnaflow cat when I put the new exhaust on.
The interior lights stopped functioning and that's a bit of a head scratcher. Tracing/testing the wires seems to indicate that the power feed from the distribution box is compromised somehow. That's a nuisance, you'd be surprised how important they are until you don't have them. Like reverse lights, and I remember not having them at some point so that switch was probably changed too. The Northeast tin worm is slowly making its inevitable appearance and I feel that 600k probably isn't in the cards, especially if it takes another 10 years to get there. Although accounting for the two years on jackstands it was really only 8 years to get from 400 to 500. Beyond all that, she's still tearing it up. After a whole bunch of seat time in the stock ETA over the last 10 years as well, it's so refreshing every time I get in an E28 with a suspension and a little bit of power. It never disappoints. I've let others drive it from time to time and have always said, don't worry about it, you can't hurt it. Just drive. I'm also pretty sure the only time she didn't make it back home under her own power was in Sept 2009 when I broke a rocker in CT, which then pierced a water jacket.
Thanks for all the miles and smiles over the last 28+ years. Best $7,200 I've ever spent.
Edit: Figured I'd better add the obligatory odo pic
So, by process of elimination going off your list the following have been replaced, drivetrain, complete, heater/A/C or at least cores/blowers, PS pump and box and more? 