I've been thinking that V has been going down the road of the bad guy recently, however, now I am thinking something else.

600 might show that V still has morals. Qarr will offer V unlimited power in return for his soul or something along that vein and V will go "how about no" and zap him - just to show us that while V may not be the moral compass of the party, he certainly isn't a villian just yet.