If Microsoft really wants to compete with Apple they should kill Office on OS X and revoke license for Windows on BootCamp and all OS X virtualization products. Though really they should have done these things 5 years ago. Apple doesn't allow Windows users to run OS X, Microsoft shouldn't allow the other way.
First, how can they revoke a license for Windows on Bootcamp? If I purchase a retail Windows license, I can install it on any PC.
Second, I don't think OS X is the real threat to Microsoft. Sure, the Mac still grows in popularity, but it's relatively marginal. The biggest threat to Microsoft is the popularity of tablets. The iPad convinced people that they can use it for the majority of their home computing. Every time the average consumer buys an iPad it's a lost or delayed PC sale. Imagine what happens when Google gets things right, and the tablet market explodes like the smartphone market before.
Even if Microsoft retains the market they are sliding into trouble. Because they can't extract the high prices in licenses for Windows and Office anymore.
Given how large a portion of business users are now buying / owning Mac laptops and/or iPads, pulling Office from OSX would probably do more to damage that very profitable business than hurt OSX. It would just push more people onto the lower cost Office 365, or Google Apps faster than they've already been going - in particular at Universities and other places where the additional functionality of desktop office is mostly wasted on the end users.
It would be a hell of a lot easier than that - simply revoke the ActiveSync licenses for iOS (and Android).
When I heard that iPhones back in 2008 (and later Androids) were going to be citizens in the Exchange world, I did a double-take... in BillG's day this would've never have been allowed.
Full-on Post-PC without Exchange (especially 4 years ago) would have been a tougher sale.
Why would anyone advocate this? The Office division doesn't need to protect any other division. They should make the best product they can on whatever OS's that are profitable to make it on. Office is a cash cow, they don't need to defer to any other division.
The original Vista Home Edition EULA had a clause preventing it from running on any virtualization product. There was such a backlash over it that they removed it later.
That must be part of the reason apple built iwork. And there would probably be antitrust issues if ms used their near monopoly in office productivity software to aid their declining near monopoly is OS software.