Most likely corporations would dominate it, because of the literally trillions of dollars in profit they could make in just a few years, provided they did it relativlely fairly. However, I wouldn't be surprised if the government threw down legislation that said citizens can grow it, just not sell it. It'd be like alcohol. You can make your own still and brewery or what not if you want, but its all personal and you need a liscence to produce it en masse and for profit.