This guy doesn't make any sense. He cites Balmer and the purchase of Nokia as rational for why Microsoft can't make something (work well) without Windows on it.
But at the very same time, Microsoft is doing just that. Many Windows exclusives have made their way to iOS and Android.
Furthermore, splitting Windows and Xbox from Bing and Azure would be stupid. Windows uses Bing, and xbox uses Azure. In a world where MS split these divisions up, Windows would then have to contract with Bing, and Xbox with Azure. And all that would happen is less integration.
I think a larger problem was that the anti-trust deal that Microsoft had to deal with included a clause where they couldn't vertically integrate as Apple did. Through 2012 (or there abouts) it was illegal for Microsoft to do so. Hell, Microsoft makes Windows N for Europe because it's still illegal for them to bundle Windows Media Player with Windows. It would be like if your mac had to run OS X N, a version without iTunes.