While I think DrPizza/Mr Bright's example of in-app-purchasing as a tool of Google lock-in was misguided, I think his point still stands: Microsoft is being encouraged from all sides to fork Android and use an hypothetical Micro-Droid OS to replace Windows Phone OS, but because of the way Google is developing Android, Android as a base OS is becoming less and less relevant. i.e. all the Google bits that are interesting to Android users (Maps, email, Play Store, Drive, etc) are Google exclusive and MS would have to replace them. Granted MS has Bing Maps, outlook.com, a Windows Phone App Store, OneDrive etc, so it has an advantage over other players, but it won't magically get millions of apps to fill out the Windows Phone App Store, because developers will have to target different APIs for the Google Play Store and Windows Micro-Droid Store, as well as getting apps accepted on two different stores.
Behold, BlackBerry did something similar, instead of forking Android, they bought in a seriously engineered OS, but whither the apps!? So they noted that a lot of Android apps just need the Dalvik VM and don't even necessarily need the Google-proprietary APIs, so they implemented the Dalvik VM for BlackBerry OS 10. That worked so well for BlackBerry that they exited the consumer market.