Actually, they make most of their money from referral traffic.

"The majority of Mozilla’s revenue is generated from search and commerce functionality included in our Firefox product through all major search partners including Google, Bing, Yahoo, Yandex, Amazon, eBay and others."

https://www.mozilla.org/en-US/foundation/annualreport/2012/f...

If people stop contributing, Mozilla is financially fine. If they stop using the browser, Mozilla is in trouble.

[Edited for clarity]

Notice I said "donations of time and labour". Not financial donations. Is most of mozilla's programming, bug tracking, promotions, evangelizaing, tech support, done by people who are salaries employees of Mozilla Corp? Or the wider "open source community"

If those partnerships were suspended, Mozilla would be in trouble. But that's not going to happen... moot now that Eich is out.