What do you think is going to cause a peak to occur? Will it be a plateau or a decline? If decline, will be be slow or sharp. Sharp as in our attempts to sustain 10 billion people leads to total collapse of the environment causing the planet to be much less habitable? Putting a number seems arbitrary even if you do use the word probably in your statement.
These people have deluded themselves into thinking the guy at the farmers market that shows up with 12 ears of 'organic' corn on the back of his cute old pickup truck is somehow going to feed the world en masse.
Organic food is a scam enjoyed by rich people whose emotions are granted more relevancy than practical thinking. It is not sustainable large-scale. People would go hungry and die.