They will end up trying to have their cake and eat it, taking money from both places. And after news like this one, many users would not want to support them, understandably.

They lost a big chunk of valuable (but not financially) user trust. It's really tricky to regain it, they would have to take a leap of faith, do "the right thing", and hope users will believe.

Or maybe we need to fork it and crowdfund (crowdhire?) firefox developers. And hope they will accept the risk of financial difficulties down the line. And there will be a long term trust/authority problem to solve - who makes decisions? But I would trust their devs personally, I think