What if we forked it with a Kickstarter campaign to fund core engineering salaries, followed by a low monthly subscription. Personally I'd happily pay if I knew the money was going where it should.
I wouldn't pay a subscription for Firefox but I would donate regularly if it was freely available and managed as a non-profit without any deals that make them beholden to megacorporations.
Probably, Mozilla could try this financing model, to save FF.
They could just jettison most of the dead weight they don't need anyway.