For those who fear MS might abandon Windows in favor of Services, here is my speculation on why IT WILL NEVER HAPPEN.
You know why? Because WINDOWS PLATFORM IS ESSENTIAL FOR MICROSOFT'S CORE SERVICES I.E. OFFICE, EXCHANGE, LYNC(SKYPE FOR BUSINESS), OUTLOOK, ONE NOTE, SKYPE, BING, MSN.
Do you wonder why IE still has more than 50% (use) share on PCs even though there are alternatives like Chrome, Firefox, Safari, Opera Mini and other available? Or why Google is pushing its services more and more with each new iteration of Android? Both Microsoft and Google know the power of owning a dominant platform in helping push forward your own services. Because most users don't bother with searching alternatives and just stick with what is available to them out of the box.
So, if Microsoft is even, at least, committed to its services, then it is also committed to Windows Platform(including one on mobiles and tablets) to stay relevant in that space.