Virtual reality in general has a lot of potential, but it will take someone really good to be able to create an ad in VR. Not only that, it also has to be an ad of a big company, otherwise it may not work at all. Why? Because VR isn't cheap. That alone serves as an hindrance already.
I think that in perspective VR gear`s price, as the price of almost any other tech prior to it, will become lower and make this tech affordable for everybody - and this will be the golden age for VR ads. They may not be present at this point as the technology is on rather early stage of development, but later, I believe, advertising companies will not miss this opportunity.