Given that the iPhone currently allows you to set either Google or Yahoo search (with Google as the default), it's most likely that if this rumor were true, Bing would be the default, but with the others remaining as an option in Safari settings as it is now.
Yahoo search IS Bing now since the deal,so no real change at all.I do prefer Bing's privacy policy,though I still use Google.I may switch yet over that.