http://news.cnet.com/8301-17939_109-10303168-2.htmlYahoo has escape clause in Microsoft search deal
(Cnet)

This escape clause is important for several reasons.

First of all Yahoo is uncertain that forming a partnership with Microsoft is a good idea. Certainly Microsoft has nothing or little to lose yet Yahoo could disappear completely if they are not careful.

But, most significantly, they (Yahoo) know that jolting their users with a very different search service is likely to cause many of them to switch over to Google rather than Microsoft. After all they have all already decided they did not prefer Microsoft. Of course Bing is new but they still can choose Google instead of being railroaded.

A search service is not the same as an application or OS suddenly losing support. It is a forced switch. The old Yahoo is gone when it is gone. So the user must switch. And if you get jolted you might as well go with Google the proven leader.

Yahoo has been around for quite some time, right? And it is fair to suggest that Yahooers did not like doing business with Microsoft anyway. And this forced switch is not going to change their mind. Once Yahoo is gone, many (or read that as most) will prefer to switch to Google.

So it is entirely possible that the combined share of Microsoft and Yahoo today will trim down a bit as Yahoo users are forced to choose between Microsoft and Google.

Hence the escape clause.

And we will not have to wait years to see if this is the case. Microsoft can pay money for years hoping it will change. But, so far, Microsoft has not shown that it can defeat Google in the marketplace.

I would fully expect Microsoft's share of search (including Yahoo) will decrease as users are forced to punt. I am sure Google is looking forward to all those Yahoo users showing up on Google. They will not all show up. But, certainly a sizable number will.