"How do you protect users from tracking without creating a backlash from the tracking industry and their customers?"

I don't see this as a concern for Mozilla. Google/Apple/Microsoft and their respective browsers sure, but the point of Firefox is to provide a browser whose goals align with the user. The industry's goals here have never aligned with users and it's about time (many, many years too late) that a major browser vendor ships this as part of the browser rather than an addon.