Very good ideas - and a proper combination of grains, legumes, nuts, seeds, can give us all of the essential amino acids that our bodies don’t provide on their own - at least for the short term.
(I’m not entirely convinced that human beings thrive optimally without eating other animals; but the science seems to indicate that we can survive - and have done - for long periods of time on NO MEAT, when we had to.)
I’d actually be more worried about the scarcity of vegetables than that of meat.
Interesting article:
https://www.livestrong.com/article/449042-can-you-get-all-amino-acids-from-being-vegetarian/
In college I lived on bean burritos and mac &cheese!
Kraft Mac & Cheese would go on sale for 19 cents, cheap bag of dried beans and cook them in a pressure cooker.
Made Giada’s Pasta primavera recipe tonight minus the squash and carrots and added garlic. Tastey
https://www.foodnetwork.com/recipes/giada-de-laurentiis/pasta-primavera-recipe-1942131