A cherished object can remain cherished after its original function becomes obsolete.

Usefulness is only one of the reasons things are kept. A tool with no remaining job, a camera that takes a film nobody sells, a machine whose purpose has moved on: these lose their function without losing what they carry, which is a person, a period, a set of hands. Keeping them is not confusion about what works. It is holding on to the part that never depended on working.

If you own one of these, use it if it still runs, or say plainly what it is for now. Naming it as kept for love rather than utility makes it easier to keep without apology.