That's what they are and have been for like 8 years. It's fine. It would be more productive to put it to good use on the browser. I'm not saying that they shouldn't have tried but... they did for almost a decade and they aren't remotely close to being able to sustain themselves without google. It's not defeatist to say that making up for the 600m$/year might be a bit of an unreachable goal at this point.
Chasing ghosts isn't more sustainable than the money from google. Yes it's a business relationship. but I'm not sure how they aren't completely "vassalized", to use your term, at this point already. It's not a potential problem, if google stops paying they would shutdown in a matter of months.
It's not a bad thing, Firefox as we know it wouldn't exist by now otherwise
A) Firefox is vastly bigger and more complicated than Thunderbird
B) Email protocols aren't a moving target to the degree that the web is
C) Thunderbird has the benefit of being able to freeload off the base platform development that Firefox continues to do, although of course it's a lot of work even to adapt to those changes.
> You want them to be Google's vassal state and wait for death instead of trying to become self-sustainable?
There's no shortage of privacy respecting open source software that somehow doesn't have to choose between depending on Google and selling out their users. Firefox knows that most people won't opt out. They're choosing to take Google's money and screw over their users at the same time.
Chasing ghosts isn't more sustainable than the money from google. Yes it's a business relationship. but I'm not sure how they aren't completely "vassalized", to use your term, at this point already. It's not a potential problem, if google stops paying they would shutdown in a matter of months.
It's not a bad thing, Firefox as we know it wouldn't exist by now otherwise