Traffic lights and security alarms affected by BT switch-off

What happens when the network for your IOT or connected devices suddenly announces it's going to make a change which affects millions of devices at your end customers? How do you convince them to upgrade to a product which is essentially the same as the one they currently have without seeming like you're trying to scam them? An interesting parallel will happen in 2025 as BT Openreach switches off the UK's analogue phone network, and millions of alarms, traffic lights, and social care devices suddenly lose connection.
Plan to retire voice network in 2025 has far-reaching consequences