Tractors are designed to last for decades with minimal maintenance; which makes them sort of the oddball item in our consumption-based economy.
It will be many decades from now, but even a new tractor will eventually get old and require parts. One wonders what if parts will be available then? For lots of us who have older tractors, price pays second fiddle to availability.
Here's one parts test we can do today: Suppose your 1978 Kubota
B7100 needs a transmission gear, head gasket, piston & rod, or 4WD front axle parts. Those were great little tractors, real basic & minimal electronics but quite expensive at the time. I still see lots of them in use. So are those Kubota parts still available from Kubota?
On our modern machines, I wonder just how useful a modern tractor is when it's computer goes out. Can it be still be used in some sort of "basic mode"? Or is it junk?
rScotty