According to the law in CO, individuals cannot sell their now legally grown personal bud to anyone, IIRC.
I don't see that many of the lazy stoners who usually buy weed from a dealer rushing out and getting all the grow equipment and then doing the research and gaining the knowledge required to grow truly quality bud like we already can and do.
Some of them will, for sure. Most of them? Definitely not.
Also, in CO, can you grow your three (or six) outdoors? I think it HAS to be indoors behind a door with a lock. That would mean most would have to buy all the indoor equipment.
I don't think dealers have anything to worry about UNTIL the government themselves starts selling, and at that point, the government could do it any number of ways.
The most detrimental to dealers would be if the government allowed the big name cigarette companies to grow, process, and sell bud the same way that they grow, process, and sell tobacco. This would also be extremely terrible for the smokers themselves. You KNOW the big name cigarette companies would flood their products with all kinds of crazy chemicals, and yet millions would still buy and smoke them.