One big problem I see with that theory is Android and WP compete directly against each other for OEM attention. There's Nokia who put their best effort with Windows Phone 7 but everyone else either did their Windows Phone 7 somewhat half heartedly, or did not do it at all.
In fact there has been some articles indicating LG is downscaling their Windows Phone effort for a number of reasons. There are only so many experienced mobile engineers in Samsung, HTC, LG, etc and companies have to decide where to concentrate. Windows Phone might gain some market traction, but I just don't see it get all that big unless it takes over Android.