Barefoot_Monkey: I think Mozilla would be wise to declare 56 an off-schedule ESR or postpone the webextensionpocalypse until immediately after the next ESR. I like the idea of WebExtensions but they won't have anywhere near enough API support by 57 to avoid very painful teething problems.
Fortunately 52 is the latest version to introduce features I consider must-haves, so I could survive going back to 52 ESR, and the nice thing about ESRs is that after a year of security updates and minimal room for regressions it's not a terrible thing if you disable updates entirely.
They wont rock the boat on the ESR releases or they wouldn't be ESR, but what they could and probably should do is despite their dug in position on the issue, to move the changes off until Firefox 60 instead. I suggest this release specifically because ESR releases come out every 7 releases and the current one is 52, so the next ESR will be 59. Waiting until after 59 would allow the new ESR to come out with existing support and have a full ESR cycle which is approximately 12 months of more support, then 60 would come out to the mainstream and 59 would continue on supported until 67 came out some time later (with 66 being the next ESR).
If my math is right, this would buy an additional 4.5 months after their current planned D-day in November for the mainstream browser to remain compatible which would allow quite a lot more addons to move over, plus would allow them to get a lot more functionality integrated that is missing making it easier for even more addons to get ported in that time frame as well. Then Firefox 60 would come out, which would be roughly Mar/Apr 2018. A month and a half before that roughly in Feb 2018 Firefox 59ESR would release with a 12 month support cycle, bringing addon support there until March 2019 or so. So we would end up going from "everything breaks in Nov 2017" to "everything gets an extra 3-14 months more time to port over to the new interface smoothly and it will be much easier for it to actually happen as well.
There's another thing I don't think they're factoring in, is that if they go and break all kinds of important addons, there are tonnes of people who currently hold Mozilla in high esteem who are going to be RIGHT PISSED, some of whom will abandon it permanently for Chrome, Opera, Safari, or whatever else toots their horn. They will lose a lot of community good will that they have gotten all along from many just by being overly aggressive without much concern for an important part of their userbase that made them as popular as they have been this long.
At this point I think the only thing that can make a difference is a good old fashioned digital lynch mob letting them know how they feel so they can re-evaluate their IMHO overly-aggressive decision.
An exaggerated comparison would be the telephone networks deciding they're going to build a new highly secure telephone network (yeah right as if they have the know how to remotely do that, but bear with me...), but it will require replacing all existing telephones and telecommunications hardware completely without backward compatibility, then putting a notice out to the world that everyone has to replace all existing telephones, answering machines, caller ID units, and any other electronic devices that currently connect to the phone network with a completely new piece of hardware that isn't even finished being designed let alone built, and you have 6 months to do it or you wont be able to make calls anymore. Not a 1:1 comparison, but purposefully exaggerated to make the point.
Look at how our TV signal has evolved over time. It took 20 years roughly from the original design bids for HDTV until it was standardized, and a schedule for rolling it out in televisions and other equipment, and turning the broadcast signal on for N years, then turning the old NTSC signal off. It phased in rather slowly and was a fairly smooth transition. No witches were burned.
Do that same thing in 3 months however and the torches come out. :)
