My immediate concern is the loss of overall biodiversity and specific genetic lines.
I'm not a large-scale farmer, but I've spent more than my share of hours in the cab of a tractor. It's already very difficult to find seeds for "heritage varieties" of many crops.
For example - for the past several years, I've grown a small patch of "Little Dutch". It's a tobacco variety that was popular in the 19th Century, but fell out of favor. To my knowledge it is not currently grown commercially at all. The only reason there are seeds available is because someone collected it from a farm in Ohio at some point.
In this example, seeds can be ordered without too much hassle... but there are relatively few vendors selling them, and I'd say it's still at moderate risk of being lost. There's a small but active hobby community around growing esoteric tobacco varieties, but that's not the case for most food crops. I wouldn't even know where to begin to even determine what varieties were grown in my area fifty years ago, much less where to obtain seeds.
In fact, this conversation has prompted me to go acquire some sorghum from someone I know that has been planting a couple of acres and processing it themselves for at least the past 50 years. They're getting older, their kids aren't interested in agriculture, and I seriously doubt they could even tell me what variety they're growing. It wouldn't surprise me if they've not purchased seed in generations. When they pass, that line will likely be gone forever if someone doesn't intentionally preserve it.