Microsoft Should...

4. Swallow Its Pride and Walk Away
This is probably the most improbable scenario with all that's been said and written, but Microsoft could shake out the cobwebs and realize that rationalizing the Yahoo assets would make the aQuantive buy, Microsoft's largest purchase to date, feel like Easy Street. There's too much overlap and difficult integration. In the meantime, Google will be in position to fire FUD missiles at will to denigrate the combined companies.