Amen to the above post! Excellent suggestions as well. 
Firefox is all about having the choice to improve one’s user experience with powerful add-ons, contrary to other browsers which seem to have different goals. I also use uBlock Origin and uMatrix with GREAT satisfaction. These add-ons increase my safety and privacy on the web and have enough credibility for me to give them the necessary API permissions. In the same league: NoScript, Privacy Badger etc.
But from @caitlin’s latest post I am confident that Firefox will divert from Chrome’s v3 manifest when necessary to preserve the abilities of our beloved add-ons, as it has done in the past. Preserving the editing/blocking features of the webrequest API seems crucial to me (not only for adblockers but for other powerful add-ons as well), with a decent warning if needed.