The terms of office of all elected municipal officers holding office at the time of the issuance of the certificate of adoption of the strong mayor form of government by the municipality pursuant to Division 2 of this Article 6 shall terminate upon the election and qualification for office of municipal officers pursuant to this Division 3 of Article 6, except that where an existing form of municipal government has the same number of wards as would be required hereunder, the alderpersons holding office at the time of the issuance of the certificate of adoption shall serve until the expiration of the terms for which they were elected.
65 ILCS 5/6-3-2