According to Microsoft, the end date for Windows 7 ESU updates is January 10, 2023. The end date for POSReady 7 is October 12, 2021. And look at this: If you apply ESU to POSReady, you get updates until October 14, 2024! If we were able to trick Windows Update to thinking Windows 7 supports ESU and POSReady, that would mean an extra 4 years of support!
And provided that Windows Server 2008 has extra support, it also has up to January 2023, meaning more support for Vista, and if we apply Embedded updates, that means more time!
Although considering Windows Vista support ended for Windows Update, that would probably not happen.