Then the hardware is not a purchase, but a lease (without time limits). And the vendor would have to refund lease payment if it stops working.

If you want to go the other way, a hardware that requires a paid service should be jail-breakable. If the designated service stops working, then the service should be open-sourced. (We would love this on HN but just imagine the OpenSource overload engineers like us would be overwhelmed with to the point no one would try.)