Until otherwise provided by law, incorporated cities and towns, heretofore incorporated under the laws in force in the Territory of Oklahoma or in the Indian Territory, shall continue their corporate existence under the laws extended in force in the State, and all officers of such municipal corporations at the time of the admission of the State into the Union shall perform the duties of their respective offices under the laws extended in force in the State, until their successors are elected and qualified in the manner that is or may be provided by law: Provided, That all valid ordinances now in force in such incorporated cities and towns shall continue in force until altered, amended, or repealed.