"large companies take over production and distribution of cannabis, the large diverse choice of strains will disappear as what is offered on the market becomes homogenized"
It's much worse than that. I can guarantee that the FDA will step in and demand to regulate cannabis just like any pharmaceutical. 100 percent guarantee it.
And that means at least two things:
(1) the cost for establishing, FDA licensing, and maintenance of GMP-standard production will be ENORMOUS; and,
(2) large companies will use plant patents (a way to patent a variety of plant - like Fuji apple) to patent-protect specific strains they create and then use ONLY those proprietary strains to run the extensive clinical trials and analytical chemistry and production/sterilization/packaging methods to gett FDA licenses for just those proprietary strains - and nobuddy will be able to afford the costs to run similar clinical trials and get FDA approval for generic (i.e., public domain strains or their own new small varietal) strains or build a facility and QA/QC/packaging/analytical infrastructure to ever gett and keep and FDA license,
so.........
... legal cannabis will very soon resemble the pharmaceutical industry - just as you have forecast. The FDA has been trying to gett tobacco under their regulatory net for a long time now, only stymied because tobacco has already been legal and established for a long time now with just a handful of large manufacturers. Pot will be an easy catch for FDA as, unlike nicotine, there is really no argument that cannabinoids are drugs and the public has treated them as drugs for a very long time now. Easy kill for the FDA vulture.
And the cost will be substantially higher.