Re: Here we go again..
If you properly modularize it, you can install on each system only the required modules, to keep the OS footprint and resource consuptpion low enough. That's why, for example, Linux can be adapted to run on different devices. And meawhile even embedded systems became much more powerful and with far more resources.
If you ever gave a look to XP Embedded or 7 Embedded, you would have found something alike already. You believe that "Microsoft's approach to coding" never changes - but they are not so dumb as you like to believe. After all, Windows Phone is already far less resource hungry than Android...