Much like last year - it all depends on how NBC's other series are going, and what demo's it is getting. Example: Vamp Diaries would be cancelled if it was on ABC, but on CW it's a hit. Also Pretty Little Liars has changed how they evaluate- big on the twitter feed apparently.
(I don't follow either PLL or Twitter so wouldn't know - but there's a huge article in EW on it.)

NBC doesn't have anything. It's only hits are Revolution, Sunday Night Football and The Voice. And it's mid-season series Deception and Do No Harm tanked worse than anything else. The mid-season series are all low-rated this year, everything from the critically touted Monday Mornings to well Smash. So there's that as well. Now, if Do No Harm and Deception had done really really well, and Smash had low ratings...than yeah.

I'm betting they'll finish the season. And I'm also guessing they are taking this risk because they know it's unlikely they'll survive.
Shows that aren't comfortable, sometimes take crazier risks.