[JohnTHaller]

Users who wish to continue using legacy Firefox extensions can use Firefox ESR 52. It will receive security updates through April 2018 at which point it will move to a later version of Firefox which no longer supports legacy extensions. Over the next 5 months, the WebExtensions API will continue to be expanded enabling more of the older extensions' features to work with the modern extensions framework.

[beezle]

Though if NoScript is any indication, they will not work as well and the user interfaces will be inferior.