Older devices become illegal, if you own one you are assumed guilty of crimes.
Non-UK, devices? Don't worry, all the countries will have this soon. The one thing that all governments agree on is that they should have more power and the people should have less.
Or on non-UK devices. This just inflates values in the UK of such devices and contents that UK will be unable to create, let alone compete with.
An 'old phone amnesty', where you take all your old phones to the police station on a given day. Anyone still in possession of one after that date gets prosecuted, like they would for having an unlicensed gun.
Maybe they can set up detector vans to search for old devices based on broadcast MAC addresses.
"Older devices could also be covered using a mandatory software update." So your already slow device will get a forced update to now make it compliant.