I guess I have a simple mind. Lets say all the humans disappeared and nothing was left but autos and non-auto's all mixing up. Then man comes along and finds this plant growing. It's a landrace to him? We start back with hemp and work forward again? Depending on which cave man worked it first, maybe autos are the norm and non-auto would be the "problem" in the gene pool?
Simple, yes, but true. The plain truth of population genetics shows us that spread of AF genes is a non-issue. That's the easy math.
When you think of how an early, smaller plant will fare, it's pretty clear that autoflowering plants would only "flourish" far from the equator, much like ruderalis now.
I buy a lot of seeds every year - vegetable seeds, that is. I buy from a lot of heirloom places and banks that actually conserve "old" and endangered strains of plants. I don't think there's any real worry about losing strains of cannabis.