Maybe it is just mean but my impression is that Microsoft should embrace RIM as their mobility partner in the same way they have embraced Facebook as their social network partner. Build the alliance with RIM leading to purchase or just extremely close partnership.
RIM essentially is the Microsoft player in the Smartphone market, a low cost easy to use solution popular both with business and the lower end of the Smartphone market. Blackberry is the mobile phone Microsoft should have made.
I know from personal experience that a few years back Microsoft had very negative attitudes towards Blackberry, butt hat was an entirely different world. Today with the likes of Google and Apple eating up the mobile market it makes sense for Microsoft to play a strong hand in an alliance than try to finally make a good mobile phone OS.