It’s a valid perspective. If there were to be a contagious disease that could rapidly spread via eg spores, it could wipe out the entire population of these crops. I am hoping that various ag labs around the country store a diversity of cereal grains.
That being said, it’s unlikely that GMO crops will stop being popular anytime soon. The best we can hope for is that labs get really good and fast at producing GM crops so that when the disease eventually hits, the lab/company can quickly produce a disease resistant variety.
The population of the world is growing rapidly. We absolutely do need highest yielding food crops if we are to not cut down every forest to just feed everyone.