Tell you what MS: You want to do this subscription thing? Here is the deal;
Free game console every time you do a refresh (even a minor refresh) with all the bells and whistles (4 controllers, kinnect, large HDD etc.), and a free replacement every time it breaks (excluding user wear and tear of course)
xbox live gold family membership
$250 Rebate to go towards a windows phone or tablet every 2 years per family member
Office365 with 100GB of Skydrive storage
Current local copy of Office Home and Student with every release (up to 2 per household member)
Current copies of Windows OS for all my home computers with every release (up to 2 copies per household member)
Zune music pass for everyone in the family
10% off at all MS owned stores (xbox market place, games for windows, metro store, etc.)
For all of this, I would be willing to pay $40-50/mo (~$480-600/year) per adult/teen in the house.
I am not a fan of a subscription services. But if you are willing to help keep me current on all major software and hardware (on mobile and game systems at least), and provide a rich ecosystem that has a lot of content within said ecosystem, then I am willing to convert and do more business with you.
Oh, and the same goes for Apple or Google: Give me current devices (even if I have to pay a little extra for higher end devices), free in-house content/software, rich all-you-can-eat web services, and discounts on 3rd party software/services and I'll be more than happy to pay a pretty penny, and convert the whole household over to your products.
But I am not interested in buying into a subscription system that is 'just office' or 'just games' or 'just music'. Such plans are well and good within their own right, but if I am only getting a single service, then I would rather buy the product outright and be done with it. Provide me with a complete and rich ecosystem, and then I'll be interested in paying monthly/yearly fees.