I'd guess even if Firefox did keep extensions unrestricted then slowly they would die away - given how much smaller the user base will be. We need some new power to emerge in this space.
I don't really get how the extension ecosystem works anyway -- extension developers are usually just sharing something they use to be helpful/make a point, and then some tack on donations thing, right? Since nobody is doing this to get rich I suspect they won't chase marketshare.
I often have a month or more long streak between every time I have to use Ch#%!e ;-)
Bonus point for devs: If it works in Firefox it usually works everywhere since Firefox had always been reasonably standard compliant.
Thanks for saying this.