There are certainly vegan protein substitutes. Although I doubt very much that crops of field corn will be turned into sources higher in protein to feed the world. Much of the land, education and machinery is geared to the selective monoculture production of specific crops. Without a source of fish, pork, beef, chicken, etc., it will be much tougher in a world under a food security threat to obtain the calories needed to sustain a healthy life. Look for a return of the great famines of India to visit us once again.
While the US population can live with a 40% reduction in yields, for a while, the rest of world cannot.







