As mentioned, Kroger arguably didn't really even sell firearms.
Very few other stores carried ammunition.
In my region, we have Fred Meyer stores and Smith's Marketplace stores (same thing - different brand loyalty). Only one of them carried ammunition. Very little of it was ever sold, even when "on sale"; because it was still expensive, it was nearly impossible to get an employee to unlock the case, and you were escorted to a register for checkout once the ammunition was out of the case.
Eliminating ammunition sales won't hurt them. If anything, it will allow greater variety of other sporting goods to be carried that will probably sell better; and employees won't be delayed for 15 minutes because Bubba Joe needed a single box of "'them Remington .30-30s."
There isn't much change. It's just political appeasement.