An EFF member has tried to convince me that Google is subject to the whims of the CAB, but failed to explain to me how. Google's Root CA policy doesn't mention the CAB, and specifically provides Google's own authority to remove CAs as it sees fit.

Whether or not Mozilla, Microsoft, or Apple follow suit, if Google were to chose to distrust a CA, such as they did with Symantec, due to Chrome's 60%+ market share, that CA is out of business, regardless of what any other browser vendor says on the matter. Whether or not the other vendors choose to follow suit doesn't change the fact that the CAB has no legal authority over Google, and Google is a significant majority of the browser market.