I don't think this will have a huge effect on the price of bitcoin, but if anything I would think it would cause prices to rise, right? It means that it is now harder to create new bitcoin, and therefore, all of the already existing ones become more valuable. I don't think it will have a huge effect though because it is very anticipate-able. This isn't going to take anybody by surprise... people who are going to buy are going to try to do it well before the halving. I think it will be a gradual rise and not a huge one.