Except as provided in subsection (b) of this section, the Board may not issue a license that has an off–sale privilege to: an establishment commonly known as a chain store, supermarket, or discount house; or a franchisor, franchisee, or concessionaire of the establishment. An establishment described in subsection (a) of this section that held a license on July 1, 1973: may continue to hold the license; and at the discretion of the Board, may change the class of the license.