However, Microsoft the company reached out to say something completely different: "We have stated publicly that all apps in our Marketplace today will run on the next version of Windows Phone. Beyond that, we have nothing to share about future releases."
In other words, they are saying that the apps will be compatible with "Apollo," but don't have anything further to say about "Apollo," including its compatibility with current Windows Phone devices.
In addition, sources have said that there will be no upgrade path from "Mango" to "Apollo." That's right, no current Windows Phones will be able to upgrade to the next major version of Windows Phone.
Sadly, that would include the Nokia Lumia 900, which AT&T has positioned as its flagship device. Apparently, Microsoft has not learned from the past mistakes of others, although, to be honest, it's not the case that Apple iDevices can receive iOS updates forever, either. It's just that since they come from one manufacturer, it is far easier for them to be updated.
Also, with "Apollo" including “Customization and Differentiation Opportunities” for OEMs, it's possible that WP8 will offer up enough of that to create still more WP fragmentation. It's always the case that OEMs want to differentiate their product from other OEMs (witness HTC Sense, Samsung TouchWiz, etc.), so this is no surprise. It might, however, make OS upgrades just as troublesome as on Android.