It should be illegal to reduce or remove features sold with a product, including charging for features that were free at time of sale. Anything less is false advertising and predatory behavior (bait and switch). It’s either free forever, free for an explicitly advertised period (on every piece of marketing and packaging), or you can’t advertise it, period. And if you ever go out of business, all associated code should be open sourced so users can continue with it if they wish.

In this case everyone who purchased existing stock should get it free, regardless of when they sign up. Only once all advertising and marketing, including packaging, is updated, they can charge future customers who purchase the devices that are explicitly advertised as subscription based. If companies don’t like it, fuck em. They’re the immoral actors engaging in the bait and switch. You don’t ask a criminal whether a law is bad for their criminal enterprise.