According to a recent Businessweek article, Apple and Microsoft are in talks to replace Google with Bing as the default search engine on the iPhone.
Without even thinking too hard, I can come up with 3 reasons why this is not going to happen.
1. Google still owns the search engine market
Even the article itself mentions that of people who use mobile search, 86% used Google in November while only 11% used Bing. Why would Apple gimp search on the iPhone?
2. Google has a way better track record than Microsoft in regards to search engines
Bing is just the latest incarnation of Microsoft's attempt to be relevant in the search engine game. From MSN search, to Windows Live Search, to Bing, Microsoft has consistently failed to gain any traction. Conversely, Google has been one top almost the entire time.
3. The Apple/Google rivalry is completely overplayed
I doubt that there is anywhere near the level of animosity between Apple and Google as the mainstream media would have you believe.