A "royalty" contract, which is based on advertising revenue generated by searches from Firefox ended in November and there has been no news from Mozilla whether that contract has been renewed or not. Typically. Mozilla chairman Mitchell Baker blogs about any critical announcements and since there has been no news from Baker in almost a month. The speculation is that Google may have told Mozilla to take a hike.
However, German website heise.de reports that, according to Google, there is a still a contract in place. Google royalties are critical for Mozilla to survive as 84 percent of the foundation's funds were provided by the Google deal in 2010 - more than $100 million annually. Common sense would suggest that supporting Mozilla would still support Google's ad revenue base as Firefox still holds about 25 percent of the market and those search revenues are nothing to sneeze at. However, a decline in market share hurts Mozilla's negotiation leverage with Google and it may be a good idea for Mozilla to diversify its revenue base.
Microsoft may be inclined to give Mozilla a good deal if it decided to promote Bing in its browser by default - and not just in a special version that is released on the side.