The terms of council members elected at this and all succeeding elections for the office of council shall be four (4) years. However at the option of the council, an ordinance may be adopted by two thirds (2/3) of the entire membership of the council prescribing and fixing staggered terms for members of the council, and the ordinance may shorten or extend the terms of current members of the council for the sole purpose of staggering the terms, but otherwise the terms of office shall be four (4) years.