>Probably all the old stuff can be brought back easily. Not anymore. They removed/replaced a ton of stuff that only was used by extensions at that point. That

>Probably all the old stuff can be brought back easily. Not anymore. They removed/replaced a ton of stuff that only was used by extensions at that point. That might lower their maintenance burden, but for the most part it really was interfaces and code that hadn't been touched since the 1990, so it wasn't like it was a huge maintenance burden before. That means it wouldn't be that easy to bring back the extension system where the old extensions would be able just run unmodified. But it would be easy enough to bring back newly created old-type extensions or modify existing old-style extensions to use whatever is present now instead of the old stuff that got removed. But then again, old-style extensions had to check anyway if a new major release broke anything, and usually it did break some stuff for some extensions. It was the cost of doing business. Jetpack/WebExtensions could help with that; if you extension was simple enough to fit within their APIs. In fx60 (esr) the removal of these "old" interfaces and other things hadn't progressed much yet, so I was able to just git-revert most of the removals that affected the extensions I care about and that was enough to run those extensions again without obvious bugs.