* Microsoft still has plenty of cash, but is facing an existential crisis of losing platform relevance
* Their overall mobile marketshare is so low that they can probably throw that cash around with much antitrust attention
* They've had a hard time attracting hardware makers other than Nokia. If Nokia stumbles further, the whole phone platform could unravel.
* The traditional Blackberry market was enterprises, who probably would be a lot more receptive to the "windows everywhere" story than Nokia's customers ever were. Blackberry's original killer feature was arguably MS Exchange integration.
If that were their route they'd have to drop their investment in QnX, try to adapt all BB software to run under the latest incarnation of Windows Phone rather than to just run Windows Phone on it. BB users are quite particular about their handsets & associated software, much more so than Nokia users ever were.
Of course this could be totally wrong but I think the challenges in moving BB to Windows Phone are far more substantial than to get Nokia to convert even if BB is a smaller player.
Just as Nokia had to drop their investment in Symbian and Maemo
> BB users are quite particular about their handsets
However they're not particular about BB10 (the QNX one you mention) since most of them aren't even running it. If anything, the fact that they're in the middle of a delicate platform shift makes the parallels with Nokia in 2011 all the more striking.
Anyway, its all just idle speculation on my part.
With 7.4 million Lumias sold last quarter, at $25 per Windows Phone license, Nokia is drawing just $70 million each quarter from Microsoft. At 10 million units, they'd start paying Microsoft money.
Blackberry sold 6.8 million units last quarter. They have no maps to license to Microsoft. If they signed an agreement with Microsoft tomorrow, it'd still take several months for the first handset to come out. What would Blackberry be worth to Microsoft in a year?
The numbers are not in Blackberry's favor. That having been said, I will never underestimate Steve Ballmer's ability to overpay for a deal.
Consider me convinced, that might just work out well for them, if they're going to switch anyway it might as well be to a company that is already well represented in the enterprise. How they're going to give those users the blackberry experience is beyond me though, but that would probably not stop an acquisition.
Now that Android phones with physical keyboards are becoming extinct perhaps Windows Phone could carve itself a new niche if Microsoft urged its phone manufacturers to ship devices with QWERTY. One thing I found lacking in Windows Phone 7 was the experience of entering text on the on-screen keyboard, especially in languages other than US English . This is a a pity because WP doesn't support alternative input methods (e.g., Swype), however, a physical keyboard would more than make up for it.
 See, e.g., http://forums.wpcentral.com/windows-phone-8/225491-windows-p.... Note that the forum post is about version 8.