Clearly you don't know what are we talking about , Compiling/Uploading your app just exact same way you already did many times for new platform/users is something most dev will do , because it don't have any burden. And as I remember they mentioned 100% compatibility , and they even support most of Google cloud service via Microsoft service's with exactly same API .
Or they could allow installing from apk or third party stores. Though that will help only the more technical users, which doesn't seem to be lumia's target market.