I don't think you'll see this for a fairly simple reason:
If we get to the point of federal legalization I think that it's going to be done on the basis of "Alright let's cut the shit, this stuff isn't as harmful as we've been making it out to be."
There is an unspoken understanding across the world, and in political circles as well, that MJ was originally criminalized for the sake of money and not actual concern over it's damaging effect on citizenry. There is, likewise, an understanding that it really does inhabit a space (as a commodity) which is similar to alcohol. Not exactly good for you, but not anything to write home about either.
Furthermore there is evidence of its husbandry dating back thousands of years. I just don't see where the FDA is going to get into some extremely intense regulatory role here. What I expect will happen is you will definitely see some bureaucratic regulation that takes place but it won't be the kind that keep strains out--it will be the kind that keeps the little guy out.
Even as a liberal I understand that probably the worst thing about government is that it exists in these "corporate spaces" to drive the little guy out. I saw a great example of this while working as a landscaper. My boss had taken to delivering firewood in the winter time (since no one needs their grass cut, lol) and he had been seasoning his own wood on our lot where we kept all of our machinery. Come to find out there's about 9 kadrillion regulations that have to be followed in order to do that legally (mostly having to do with fire hazards). To comply was prohibitively expensive with a capital P, so much so that it drove him out of the business (or it would if he followed the regulations which he does not).
So I would expect to see this type of regulation coming down from above rather than something that's actually targeting the plant itself. Ultimately the little guy suffers and those who can cover the overhead do alright. Really it is this type of thing that drives forward the process of a market becoming perfectly competitive (that I brought up earlier). When there are barriers to entry that everyone has to pay homage to it levels the playing field--but it also installs a glass floor for what it takes to be a part of the business.
Ultimately its the consumer who controls whether or not a glass ceiling comes into play. If I had my guess I'd say they will, but that's what 90% of this argument has been about and its really anyone's game. I think most of us know the price floor will raise over time (there is already one there by way of equipment, water costs, nutrients, etc). As the floor/ceiling meet each other and the margin shrinks that's where the basement grower will find difficulty. Without sufficient scale one misstep puts them out of business.
