All laws relating to the school board, library board, hospital board, airport board, housing authority, plumbers or electricians board, planning board, zoning board, park or recreation board, municipally owned public utility, and any municipally owned service enterprise, including inter alia, electric, gas, and water boards, agencies, etc., and any board, authority, agency, etc., given such independent status, as the same may apply and be in effect at the time when such municipality shall elect to be governed by the provisions of this article, shall continue in full force and effect and without interruption or change as to the establishment or conduct of any such authority, board, or agency, until otherwise provided by law.