Any municipality which adopts the council-manager form of government under this article shall continue its existence as a body corporate without change in the municipal corporation. The word “municipality” as herein used shall mean and refer to any municipal corporation which elects to come within the provisions of this article. The municipality shall continue as a municipal corporation within the corporate limits as then established, including all annexations, and as thereafter fixed in the manner prescribed by law, subject to all of the duties and obligations then pertaining to or incumbent upon it as a municipal corporation, and shall continue to enjoy the rights, immunities, powers and franchises then enjoyed by it, as well as those that may thereafter be granted to it.