If you aren't looking at capturing 100% ewaste, then simple laws around liability and penalties for reduced functionality is all you'd need.

Simple things like "if an electronic device, through no fault of the owner, can no longer perform it's main function, then the owner is due a full refund. A company may escape the refund by placing all software required to run the product in the public domain."

It'd miss cases like fly by night companies, but you could catch big players like google disabling their thermostats for non-hardware reasons.