When I used to work in defense contracting, this is precisely what we (the contractor) did. We would buy up all available stock of any difficult-to-replace parts (often specific SBCs) when the manufacturer announced end of life.
There's a market in conforming interface and ABI spec meeting hardware to emulate the boot and upgrade devices for German tanks, or some other hardware. Sd card or USB behind, giant milspec plug to the fore.
