Idea: Prosecute such companies for obtaining money under false pretenses. If you only get the thingie which you "bought" for a limited time - that is clearly a rental, not a sale.
It’s tough because what if the company doesn’t want to maintain the software? Are they obligated to keep the software up to date despite the one-time-sale? It’s a similar reason why much of the software moved to a subscription model, the recurring costs. Alternatively, there should be some group of smart individuals who come up with some protocol for various devices where, if a manufacturer decides to EoL the sale (s…
If it's a security issue, then it was sold defective.