Then they just set the list price too high, always sell with a shrinking rebate, and it turns out that nothing changed in comparison to as so it is today. Nice idea...
In case of this law passing they will raise prices to cover costs for supporting old hardware. But I, perosnally change phones every 2 years becuse I like new techology and do not want to pay the price for supporting obsolte hardware which I do not use. Proposed law should balance benefits of people who want to use old hardware vs. ones who one to upgrade often.
This would probably increase resell value of your old devices so most of the cost would be returned if you resell your device.