As a Blackberry Z10 owner (who has also owned several generations of iPhones and Nokia's Lumia 920) I think BlackBerry needs to stick it out. The Z10 has a great OS. The touchscreen gestures are ingenious. The Hub (where the email and notifications are) is a fresh innovation.
The device in general is well thought out.
Also important to note that the Z10 has privacy and encryption features no other phone I know of has.
Blackberry has something good, and while Google and Microsoft continue to hemorrhage users because of trust violations, BlackBerry can win back market share. It can happen!