Could apple change their developer contract to say anything they want?
Bing Maps will do fine. Bing search will do fine for a large percentage of users. Youtube will be missed but its web app is pretty good now.
Assumptions that Microsoft is cozy with Apple are flawed. Microsoft is more at risk from Apple than they are with Google
War at the PC vs Mac/iPad front is a different thing, IMO.
In fact, if Apple were stripping out Google ads (as per some rumblings), Google would have a basis to demand that all it's affiliates stop serving to iPhones as well.
War would be hell at that point. Probably some lawsuits in the making.