I doubt this will work. Would you as a nursery man be willing to reserve a large space of your greenhouse for plants that you can only sell in the next five to ten years? And them hope the species you dedicate so much time and space on actually will (still) be popular after a few years. in the mean time hoping the species has not spread via the many seed lists that are out there already so you can actually benefit...?
(And why should only commercial nurseries be benefiting from this. It is not like they have high priorities of getting the prices down of plants, or are expected to have an altruistic view on plant distribution)
I see much more sense in for Mexican authorities to distribute seeds (collected from colonies that can easily miss a large quantity of seeds) to the many succulent societies (like the BCSS, Succulenta or the many Czech societies), that should distribute these to their most prominent members whom are willing to dedicate their time and knowledge to propagate these species further. With grafting you can get up to speed for seed distribution to everyone interesting in a certain species quite quickly in societies seed lists. In a few years the pressure should be off for most wanted species as everyone had a chance of obtaining them, theoretically.
Sounds like a better solution that keeping the pressure on species for decades by banning them fully and just making things harder, allowing unscrupulous types to make easy money in the mean time. That will be a never ending story...
I am totally in favour of being openly and transparent, making things easy instead of hard and try to facilitate as much as you can in a controlled and orderly way. This will benefit the colonies of plants, the societies and their members.