Flex certificate expiration of SWZ

If I recall, around March 6, 2015 Flex SWZ signed RSL file certificates expired - files such as framework_4.1.0.21490.swz.  Adobe provided new SWZ with an expiration in 2025, perhaps.

Think this thread covers the topic: https://community.adobe.com/t5/flex/error-2046/m-p/7163788?page=2

Working with a company that's deployed Flex solutions for over a decade, despite offering a new HTML5 based solution there remain clients who will not upgrade.

Any insight or reommendation into the future here?  Presumably there will be no future updates to these files?  

For reference, these clients are internal kiosks at mechanical plants, accessible via intranet on the plant floor.