Part of the reason why Apple and Samsung have become so dominant in the mobile world is that they have an ecosystem of products. BlackBerry used to sell a tablet, but it just announced that the PlayBook won't be getting updated to BB10. In fact, the CEO said tablets would be dead in 5 years--before backtracking.
Apple and Samsung also have products for the living room in Apple TV and Samsung's smart TVs. That makes it harder for BlackBerry to compete when it has a single device that can't connect to anything else.