Shouldn't the number of people raising chickens have already reached a market equilibrium?
1) Farming chickens requires capital investment that might not be available to poorer families. Equilibrium can only be reached if the would-be-chicken-farmers have easy access to credit.
2) Chickens have inherent value; you can consume the eggs yourself as a substitute for other goods you were going to buy, and the meat as well.
If the price goes down then the farmers eat more eggs (and chickens, if they want), which is still a good outcome.
Owning the chickens means owning capital, not being a waged consumer. Chickens also have inherent value, being able to lay eggs and have more chickens. Also many suggestions in the article about empowering women, which compounds the impact of capital ownership. Mainly marxist interpretation.
Owning chickens means a surplus of chickens, and therefore there will be no more grain. Malthus.
Price of grain/feed will change, but assuming chickens eat grain + anything, it might not change that much. Added benefits of immunized chickens. Unknown effect of price of chickens, perhaps deflationary pressure on price of other goods. Ricardo, perhaps.
The network effects will be interesting. Every house with a couple of chickens is very worthy selfsustainment.
A form of basic income.