According to the verge Nokia stated in a SEC filing that Microsoft has the surface phone as a plan B or even not putting as much money into to WP...or worse having it discontinued.
http://www.theverge.com/2013/3/9/4082036/nokia-sec-filing-microsoft-smartphone-hints
http://www.theverge.com/2013/3/9/4082036/nokia-sec-filing-microsoft-smartphone-hints