Collaborative partnerships between parties can propel strategies that get the job done. The growth of store brands proves that such commitments drive sales and loyalty over the long term.

Today’s food marketplace is a bit like the warring factions on HBO’s “Game of Thrones.” All of the parties in this channel-blurred landscape—drugstores, c-stores, dollar stores, grocers, e-tailers, discounters, you name it—are locked in bloody, hand-to-hand combat.