Speaking as one of those BlackBerry diehards, it seems to me that MS should have its crosshairs on RIM at the moment, not Apple or Android. Those two Goliaths will be way out of reach for a while. For now, the battle is for third place.
I like the BB. I bought a 9900 and don't regret it a bit. It's still my "main phone"; the Radar is my "experimental" phone. But I keep an open mind. There are things I don't like about iOS and Android, so I want someone to do a better job, eventually. At the moment WP and BB are the two contenders.
People scoff at BB these days, but even with BB10 probably farther off than Apollo, BBOS7 still has some advantages over WP7, so the first job for WP should be to close that gap. Since smartphones are, for many users, primarily about communication, MS should be paying close attention to ease of communication. Since the virtual keyboard is still the primary input method, MS should be working hard to improve it. It's not bad, but could be better. There should be Swype, or something similar. People need options, when it comes to output.
And they need options when it comes to output. That includes more flexibility in notifications, sound profiles, etc. BB lets me creates as many custom sound profiles as I want, and this isn't really a frill. People who use their phones in a wide variety of settings need to be able to switch between profiles easily.
As I've pointed out in other threads, the way text is displayed on the screen needs to be more configurable, especially in the browser. People have different eyes and different visual requirements; one size does not fit all.
I think MS is already doing a good job getting developers interested, and landing apps. There is good growth in the Marketplace and many of the "name" apps are there, even though there are still some missing. On the whole, I think the trend is positive. Here's where WP can surge ahead of BB, since there's little developer interest in OS7 while everyone waits to see what BB10 will do.
The issue with Facebook updates and the People hub may not have a ready solution. I have mixed feelings about the whole People Hub concept anyway, and I'm tempted to disable it, assuming that's possible. When I want to see FB updates, I'll open FB. When I want to read tweets, I'll open a Twitter client. I don't need to have all of that being constantly fed to my phone. Maybe I'll come to like it, but at the moment it's too reminiscent of MotoBlur, which I didn't like either. I delete the Social Feeds app on my BB for the same reason. But that's just me.