Windows Phone 8 has been just launched.
There are more Windows Phone 8 models now than we had all previous Win Phone models combined.
Within a quarter or two..Windows phone will see a good jump..due to being developer friendly as well as ecosystem friendly...(you get same API and platform to develop both Win and WP8 devices... and ecosystem with IE,Skydrive,Bing,Xbox) . (both of which made iOS a great platform)
Also Android came from back from iOS(almost nil marketshare) and went to gather the biggest marketshare right now because of its price.
So from these points..clearly Windows phone has the best of both other operating system..price/ecosystem/developer friendly.
It is just late to the party!..
So it will definitely become huge.. but not get the biggest marketshare.