I'd say a CEO that understands the development process and how Microsoft works, from a technical perspective (like BillG did) would be a good requirement, but someone from the outside wouldn't necessarily be any better just because they came from outside Microsoft. Any time an analyst finds fault with Microsoft because they don't have the #1 mobile platform, and thus says "they haven't dealt with the move to mobile" shows their lack of understanding of what Microsoft does - make backend software to run on-prem, hybrid, or totally in the "cloud" (whether it be Microsoft's or otherwise), and a user-side platform that provides the basis for those apps to be accessed.
To that end, I'd personally love to see the shift to total app compatibility between Windows 8.x "Pro", RT, and the Xbox and mobile (WinPhone) platforms, but with people decrying RT and WinPhone because of a lack of apps - and then most of those same people go looking at, for example, the Ubuntu phone platform and drooling over the ability to run apps anywhere - I am sort of drowning in misunderstanding and irony here. I know it's Gartner and Michael Silver, but.... he's just like almost every other analyst and investor out there who fails to see the long view of where Microsoft hopes computing will indeed go - mobile devices that rival what's on your desk today, with access to local apps or apps on the local network or cloud, storing your data and being able to get to it anywhere, because all the devices will run the same software and access the same services. It'll take 10 years, likely, for it to be a reality, and Microsoft wants to "pull an Apple" and see what others do, do it better, and be the first to get there.
It's so sad to watch these talking heads miss the forest for the trees, and they do it so often you wonder how they still get a pulpit to speak from.
To be fair, I have NO idea if it'll work or not, but the odds are things aren't going to go back the way they were, so instead of spending time putting the genie back in the bottle, make the genie work for you instead? I'm not a CEO, so I don't know, but it seems like a good idea to me.