When people ask why Nokia isn't selling a lot of Lumias, most people, correctly, answer "Windows Phone". Going with Android puts them in a much better position than Windows Phone for a lot of reasons, and every negative that can be said about going with Android (minus the OS differences) can be said about Windows Phone. The only difference is that Nokia is pretty much the only OEM that is all-in with Windows Phone, but once WP becomes popular, whats to stop Samsung, etc from making more WPs? Nothing really, and at that point, Nokia will only be able to distinguish itself with its hardware (since there are limited/no OEM/carrier modifications allowed to WP) which is WORSE off than if they were using Android right now.