Firefox took marketshare from IE when that was impossible. It could do it again with Chrome, if things change a bit. Some problems with Mozilla are that they don't do community management well any more. In the old days, there were amazing grassroots-driven projects like spreadfirefox.com. It is not like that any more. Grassroots supporters have trouble participating, even if they try. For example, I tried to create a…
For Chrome on the other hand, its near-monopoly situation is worrisome but it's actually a pretty good product. So there is no pragmatic reasons to leave it for Firefox, only ideological reasons and it's a driver nearly not as powerful as suffering every day.