XBox (independent) vs. Sony, Android and Apple is a losing proposition, they may as well sell the division. In a high-stakes game like that, you need a parent company with deep, deep pockets.
Windows independent of Office is worthless. There's virtually no reason to use Windows apart from the Office infrastructure built around it, or the entrenched base Visual Studio developers. It's somewhat popular as a gaming platform, but as Linux starts to be reshaped into a first-class gaming operating system, that will quickly become a non-factor.
The online division is the most troubled, basically a black-hole for money. Surely it could be made profitable, or simply sold for a massive chunk of cash to someone like Yahoo! who could afford to pick it up.
It's not that the divisions would do better independently, but they're part of a highly dysfunctional family that cannot survive independently.