The US government is one of their major customers, and a lot of business men and women like the piece of mind their phone is DoD approved for security... Even if they do nothing else to secure it.
-Retracted-
Your correct they did push BlackBerry10 in 2013, but BlackBerry 7 (No clue what happened to 8, and 9) was not an upgrade from 6 and was only available on newer phones. Which leads me to believe 7 was actually the QNX implementation.
OS: Blackberry Tablet (QNX)
From the BlackBerry Tablet page
"Another QNX-based operating system, known as BlackBerry 10, will replace the long-standing BlackBerry OS on handsets after version 7."
Android is a time-shared monolithic kernel.
QNX is a Real-Time Microkernel.
So you want to pay people to maintain 2 different kernels, for the exact same hardware, at the exact same company? When the primary customer of your phones are only interested in mobile email?
To make Android profitable you'd have to complete change their target demographic, and re-invent their company image from, "Phones for lawyers, and non-tech savvy business people" to "Phones for everyone."
That's a drastic shift.
> To make Android profitable you'd have to complete change their target demographic
While I'm not sure agree with the aforementioned commenter, I'm not sure I agree with this either. Trying to shift to "phones for everyone" is what has left BlackBerry struggling now.