Production is solved for now, but our solution (at least in the US, as I understand it) depends on abundant supplies of fossil fuel and fossil water, which are not going to be around forever.
So, there is plenty of work to do to see that this problem stays solved.
Abundant supplies of fossil fuel's are in use because they are cheep. Zero technological advances are required to provide a stable food supply for 20 billion people. It's actualy difficut to find the maximum stable food supply with current technology over the long term.
For example: "there are 1.3 billion cattle in the world today"
Now some of them are a net food source because they feed in areas that humans can't. But, effectively feeding cows costs the world well over 1 billion humans worth of food.
Topsoil does not actually get destroyed. Rivers just deposit it as silt which can be recovered.
fossil water is not an issue - aquifers are constantly replenished with rainwater (and manual recharging via pumping treated water back into the aquifer...a debatable idea). At least that's the case in the mid- and north-west. Coastal and dryish states may vary. I seem to remember seeing somewhere that Los Angeles was putting an evaporative water purification plant in, which would give the aquifers in that area a rest.
So, there is plenty of work to do to see that this problem stays solved.