Close to $400 - $500 I believe, way below that is bad for the miners already.
Once the bitcoin price hits 1,000$ it maybe drop at max 850$ and it will be in sideway for 1-2 months after that it will grow up again.
I expect the new top price hits at 1,260$ in September, 2017.
$1,200-1,400 would be a perfect target range for 2017.
Actually it's already good if the price maintains like that. Price jumps are due on the next halving season again.