He can finish that is for sure, a lot of the rest of his game I can't say I rate as highly though. When Cazorla scored was example of that, could barely get the ball out of his feet.
In quick lightening breaks he is lethal but how often are we in that position? More often than not teams will defend deep and something as simple as that and Theo is out of the game, he needs to have much better ball control in order to really become a top player and worrying after all this time his control is still a lot of the time very erratic. The wings are perfect for him as he'll have space on the ball and can make those kind of diagonal runs but the media and Theo have it stuck in their head he is a striker.