Google also could cut off Mozilla's funding in a heartbeat. Since their management is incompetent (but their engineers are awesome and I love them), they haven't done any serious attempts to diversify their sources of income, or at least to put some of that cash away for a rainy day. Firefox is just as dependent on Google as are any of the Chromium rebuilds. (I am writing this as someone who has been using Firefox since about 2006 non-stop, seeing its market share drop by a factor of ten in that time).
