I doubt it wil be set up-able but there is a timer running out and a kill counter going up. So i assume they can say after X minutes the team with the most kills is the winner. And if there is a draw then i really hope that it goes down to sudden death between the teams. Thats would be fricking awesome! But yeah im sure they have this in as i have seen it in the videos i have watched.
I hope they will, because Blizzard aren't going to focus a lot on creating different kinds of game modes for PvP nor PvP in general so it would be cool if players themselves could create the modes or made suggestions for Blizzard to implement so we can get some original content into the PvP and not make it a bad copy of certain MMORPGs