At last some engagement!
Those other crops (which other crops are they?) cannot produce anything like the calories per unit area that grains do. It's all about the efficiency to harvest sunshine. We are running out of arable land and losing much constantly while every day there are a few million more mouths to feed. Aside from the obvious that we cannot keep reproducing ourselves to extinction this implies the need for more food per acre of land not less.
Have you read about the green revolution? Start with Wikipedia. For the current situation go to the FAO they have been grappling with this for decades. Those are the kinds of figures that make your scheme impossible to apply generally. As Fran said, what you suggest is only possible in rich societies.
Assuming that what you say about yield and cost are true about California wine you cannot extrapolate this to your scheme to do away with carbohydrates as a major component of the world's diet. For a start their measure of success is to produce quality wine not feed the maximum people per acre.
No it isn't. You merely assert your case but I need you to produce some evidence.
I am mainly organic but I would describe my approach as eclectic with a bias towards recylcling and away from introduced inputs. I have no need of ammonium nitrate as I can get N from manures. But I will use Potassium sulphate as there is no other practical way to get K into my soil.
This is not relevant as I am not trying to feed a family on my vege plot.
Let us not get too distracted by the specifics of my garden, you need to show how the world can still eat by doing away with 2/3 of its calories that come from carbohydrates. And show the FAO how to find a way to feed those millions of poor buggers who already don't get three squares most days. And the millions extra that will be born daily until we get means of population control other than starvation and war.