Just a few years ago, Mozilla's Firefox browser was rising fast as the chief challenger to Microsoft's stubbornly dominant Internet Explorer. Things change pretty fast in the world of Internet technology, however, and today Firefox's once bright future seems much less certain.

In 2008, Mozilla entered into a three-year partnership with Google. In exchange for remaining the default search engine on Firefox, Google hands over about 84% of Firefox's total revenue. Well, it's 2011 now and, as ZDNet's Ed Bott points out, the status of that partnership is unclear.

Back in 2008, Google's own Chrome browser was just getting started. Today, it's a huge success, having recently ousted Firefox as the #2 browser, according to one source of browser marketshare statistics. So far, Bott's inquries to Mozilla about whether or not the Google deal has been renewed haven't yielded a straight answer. It's entirely possible that Google won't renew the deal, which would put about $100 million of Firefox's revenue at stake.

Not only does the search giant have its own hugely popular Web browser, but it now has the Android mobile operating system, which is also growing fast. The value once inherent in being the default search engine in Firefox has declined as Google's tentacles have extended into the browser and mobile spaces and Firefox's growth has slowed. Google doesn't need Firefox anywhere near as much as Firefox needs Google.

The Mobile Revolution Isn't Helping Firefox

Making matters worse is the explosive success of Apple's mobile devices. Naturally, the iPhone, iPod Touch and iPad come with Safari as the default browser and any third party iOS browser has to be built on WebKit, rather than the Gecko engine Firefox uses. The only presence Firefox has on the iPhone and other iOS devices is an app that ports one's bookmarks and other browser data to the device.

At the moment, Firefox's mobile focus is on Fennec, a browser that's available on Android and as an alpha on Windows Phone 7. The rapid growth of smartphones and tablets over the last few years, which is only just getting underway, have not been much of a boon for Firefox.

Now the majority of its revenue is in jeopardy, potentially putting its position on the desktop browser market at risk. Still, Google isn't the only search engine. If they pull out of the partnership, that leaves an attractive opening for Microsoft, who is always looking for ways to challenge Google with Bing. Users of Microsoft's browser already have the option to download a version of Firefox with Bing as its default search engine.

What do you think? Is Firefox screwed or will the browser find new ways to turn things around? Let us know your thoughts in the comments.