That is an interesting question since it could be hard for Microsoft to explain this to its consumer customers. I think that the core apps, like Mail and Messaging will be updated more frequently. Also, some new features could be pushed via Windows Update.
But it is really tricky to compare the mobile, heavily consumer-oriented platforms to Windows. Since Microsoft supports its products way back because of its enterprise customers, it would be really hard for them to support, let's say eight concurrent versions of Windows.
If you don't count IT departments of developer-centric companies, where developers (at least from my experience) can be really vocal about needing or wanting the latest software, it is nearly impossible for big corporations that have a lot of investment in custom applications to deploy a new version every year and would effectively mean that most corporations will never have the most current version of Windows.
So no, I don't think that this will, or should for that matter, happen.
