Microsoft makes 25% of it's revenue from Windows. And an equal amount from server and tools(this is where VS belongs). Xbox makes 13% and Bing 4%.
Office makes up 32% of the revenue. If MS can sacrifice a part of the 25% which VS is a part of and retain or perhaps increase the net revenue from other segments ( by attracting developers), then it will be a successful move.
Attracting developers will only be half the game. It will still have to find a way to ship more devices with Windows and for that it will have to make Windows devices and phones primarily an attractive option.
With most consumer computing now occurring on mobile devices, sales of devices with Windows will determine Microsoft's future. The consumer segment will have an effect on the enterprise segment as well. Microsoft will then end up eventually losing all their revenue streams.
http://techcrunch.com/2013/09/19/microsofts-business-in-thre...