Maybe massive move to hydroponic farming done on sea rafts or something. Or on those whirling space stations with artificial gravity . 3d - printing food (if you believe in bioenergies first print some living tissue then kill it u done) is an option. Harvesting plankton is an option. Cultivating airborne plankton and such for protein is an option.
The guy is right (I know nothing about the guy himself): if the current trend continues we're left with desertation. We need soil - producing agriculture and the current one is soil - destroying. It doesn't need to be economically viable in itself. It could be subsidized for common interest by the public sector.
That implies an 8x increase in costs, I heard in the past few days (cannot remember the source now).
So: realistically - i.e. taking into consideration game theory on political and economical [game] rules?