BlackBerry is known for their top notch set of business applications on a solid piece of hardware. What they do not have is an application Ecosystem. I think it was a little greed and little closeness of their Ecosystem that did not invite the developer community to write applications for them. Let's face it they had the market for a long time and for whatever reason was not able to capitalize on it.
So BlackBerry here is the plan and yes you will need to concede and work within a flourishing open Ecosystem where unless you are original and keep innovating you will not survive. The plan would be to do what Amazon has done but with your phone and provide the same awesome user interface that the business has grown to love but underneath is android. This will allow you to partner with maybe Google or even amazon to host their application store or even better provide a curated application store for the business community! But you would stand behind the OS and your applications on your hardware to be secure and reliable like the past.
The only reason why I see this not working is pride on BlackBerry's part. Amazon has proven you can have successful branded version of android and be successful. The lawsuit crap between the super powers has finished so you will not be brought in to the courts. Let's face it too you would not have to spend as much on development from the ground up. Google is doing this you might want to have a team work on an addition and contribute back just like any other OS community.
Well people know I am a fan of android. one reason the OS community creates the best products just look at any big product company and under the hood there is OS everywhere.
There I said my peace to myself and if you want to read have at it.