Microsoft has indicated that Windows 10, which will be released next year, could move towards a subscription-based model. Instead of going the usual route and buying a perpetual Windows 10 license for $50 to $200, you would instead pay a few dollars per month -- and then, as with most subscriptions, you'd get free upgrades when major new versions of Windows come along. Another option might be that you get a basic version of Windows 10 for free, but a subscription would unlock more advanced features.