That really doesn't solve the problem, like every other Firefox fork they're completely dependent on Firefox. You can't just make a new webbrowser just like that, and while third party developers can certainly disable some anti-features, there are limits to that and they can definitely not do the basic work that the Firefox devs do (or could do, if Mozilla had different priorities).
Mozilla spinning off control of its development to an independent group the way they did with Thunderbird would be the best thing that could happen to Firefox.
Operated by MZLA Technologies Corporation, a subsidiary of the Mozilla Foundation, Thunderbird is an independent, community-driven project that is managed and overseen by the Thunderbird Council, which is elected by the Thunderbird community.
Chrome self-destructing because of stupidity like AI would only ever manage to be a close second, at best.