The blowback will not be felt at the grocery stores, it will be felt in the political process. The demand for cereal in a typical American home is not elastic. It will be bought and consumers will collectively distribute their ire elsewhere.

Mom: "whelp, we tried the democrats and now my groceries are outrageous."

Gasoline, rent, shit service...it is not going unnoticed. I quit going to Starbucks because I had to wait a half hour for a simple menu drink every single time, busy or not. I can just stop going there...people can't stop buying cereal and milk, rather they won't and now have elevated expectations of government to control prices and their general well being.