> If you did want your software project to run the same as today when compiled/interpreted 10 years from now, what would you have to reach for to make it 'rot-resistant'?

Target Windows, avoid Linux.

ABI compatibility is one of several components involved. The OS the software runs out plays a small role in this problem.

There is a relevant point about OSes though, and it has a different conclusion from yours: Write our software (And OSes) in a way that doesn't create barriers and friction between systems.