Saying "could stop working" and "won't get updates to the trusted root CAs" is all future issues.
How long should Apple be required to provide updates, both security/vulnerability and future API support?
Currently, iPhone 6S, released in 2014, can run iOS 15, which received its latest update in 2025. The iOS 15 apps work with Apple's services, some with reduced functionality because it was never in iOS 15.
So that's a 10 year old phone.