To a certain degree, isn't diversifying kind of antithetical to the niche grain serves? That is to say, it seems like the whole role of grains is to be a fairly generic source of starch. I'm not sure that you could diversify much while still serving that role.

Point taken. I think the "grain industry" has that problem, but no individual farmer is duty-bound to go 100% on grain for export every year. For example, they could grow grain crops intended for consumption in the US as a hedge against the (predictable) disruption in export markets.