If we have a magic wand and that disappeared entirely tomorrow, that would simply be allocated to other areas. There’s a reason sodas in the US are sweetened with HFCS and our gasoline is cut with ethanol produced from corn - because of lobbying efforts to subsidize corn production, which has driven down costs, which in turn made it profitable to use corn in ways where it wouldn’t otherwise make sense. Europe uses ethanol derived from sugar beets, which is significantly more efficient in terms of CO2.

It’s significantly more complex than “if we reduce beef consumption, we’ll reduce corn consumption”.