Unfortunately, this issue has been litigated many times in US courts and it all comes down to the terms of service.
The smartthings terms of service, which you agreed to when you set up your smartthings account, says they can discontinue anything at any time for any reason. I know most people don’t read the fine print, but it is in there.
Will SmartThings ever change the Services?
.
We’re always trying to improve the Services, so they may change over time. We may suspend or discontinue any part of the Services, or we may introduce new features or impose limits on certain features or restrict access to parts or all of the Services. In some cases, the changes we make to the Services may cause older hardware devices, third party services, software configurations or setups to no longer work with the Services, and you may be required to upgrade or change these devices, services, configurations or setups in order to continue using the Services. We’ll try to give you notice when we make a material change to the Services that would adversely affect you, but this isn’t always practical.
They have a separate issue with warranties, which is why they are offering a “full or partial“ refund for panels which are still in the warranty period. But again, this kind of issue has come up many times before, and at least in the US, a legal case unfortunately won’t get you anywhere.
See the current discussion thread for more about the “retirement.“