It's silly to think that legalization will rule out the possibility of profits for the small people, just as it's silly to think that there will somehow be an impact on the strains available to grow.
Even if licenses were only given to the megacorps, it still wouldn't change a thing. If these large companies don't sell what people want, then there will ALWAYS be people saying sod licenses and legalities and just continue growing just as they do right now when there are no licenses. If the governments cannot control the production of cannabis when it is illegal, like hell they will be able to do so when it is legal. If there is only Monsato lights or whatever, there will always be those hundreds of other strains available through the same channels as they are available today. The only real difference is that thee growers will have to have a genuine reason for their prices. Largely, i think growers are just scared that they might actually learn how to run a business and offer a competitive product. It's much easier just to have it illegal and use the old "risk" excuse to charge ludicrous amounts.