> Quite the opposite is true (I believe) since a ton of users would leave Firefox for alternatives.

Yes but keep in mind that’s not an individual problem that is solved by switching browsers. If a browser engine dies, the walls get closer and the room smaller. With only Chromium and WebKit left, we may soon have a corporate owned browsers pulling in whatever direction Google and Apple wants. I can think of many things that are good for them but bad for us. For instance, ”Web Integrity” and other DRM.