You've done the required maintenance, the car is kept in a garage,
there's nothing else to do. Of course one CAN change the oil more
frequently but the engine isn't what's going to wear out in the next
100K miles. Other things like the fuel pump and / or its relay, the
water pump, muffler, perhaps the fuel gauge or a door lock - all things
that receive no maintenance because none is due - but nonetheless break
due to wear and the electronics due to age.

The car's depreciation has virtually ceased so some repairs will be its
only expense. Buy a AAA membership so you can get help when it breaks.

I own a '80, which like your car, is well maintained and garaged. A few
years ago I had the then 20 year old door seals replaced, I also had to
replace the rotted horsehair pad under the back seat (even though it
received very light use). The mechanicals are fine, the paint is fine
and the windows don't leak. The rubber suspension bushings are now hard
and transmit some road noise but are fine otherwise, in fact the whole
car works astonishingly well - not much differently from when I bought
it in 1980!

A/C recharge , Rotor, Distributor cap, belt tensioner and new belt, front
timing cover gasket and valve cover gasket, flex disk, motor mounts,
bushings for shifter rods, radiator hoses, l fan  were my only issues to fix
at 126k miles. I bought the car with 122k miles and it appeared to be well
maintained.

Peter

Thanks to all who responded.