The problem with design was a speed bump they ignored almost a decade ago...that ship has long sailed and left Blackberry behind.
The biggest issue Blackberry faces today, and the one that will ultimately lead Blackberry to being sold, in my opinion, is the fear investors have in the company itself. Investors view BB as a lame duck...and they've been advising a sale since 2012 (when Google first threw an offer out, then again in January when Samsung did the same...both times Blackberry turned the sale down because they felt they could achieve a monumental comeback).
Eventually, investors are going to start jumping ship all together, driving the stock price down even more than it has already...then the company will sell for peanuts because the board at Blackberry has this magical idea that the way to fix their sinking ship is to focus on only a portion of the holes in the hull...all the while, some of the largest holes are ignored (AKA: The consumer market), and the water keeps flooding in, while these BB heroes stand proudly at the holes they focused on (Enterprise), ignoring that the ship is still very much sinking (even quicker now).
Personally, I've always thought that Microsoft was the most attractive potential buyer because A.) Their own devices haven't found immense success on the market in either quadrant, and B.) Windows is to corporate and government computing what Blackberry has been to mobile devices in said circles. It'd make sense that Microsoft, in an effort to continue (and grow) their relationships with the government and corporate America, would buy the company that focuses on the same in the smart phone market (which Microsoft has never cornered anything in).
We'll see.