Re: I don’t understand your reasoning
Anything currently running on old hardware is kind of irrelevant.
Aside from very specialist (expensive/embedded) environments, the main reason why really old stuff is still used is because it still works.
There is usually something newer and slightly better to shift to - the reason they didn't shift before is because they didn't need to, not because they couldn't.
So it'll stay on that hardware until it physically dies.
Then it'll either be obsolete and not needed, get updated to whatever hardware is easy to buy at the time of death, have the hardware replaced like-for-like from Ebay, or have a lift-and-shift into a virtual machine of some kind.