For me, the WebExtension transition isn't all doom and gloom. But I can't assume everyone uses the same addons as me. The transition to WebExtensions is nearing and a lot of extensions people use just don't have a viable replacement.
I only know about Cookie AutoDelete, and it's great that it exists but, sadly, it's not yet mature enough - mostly because WE APIs are lacking. For example, there is no localStorage support, and there are bugs like https://github.com/mrdokenny/Cookie-AutoDelete/issues/83