Any municipality that is not located wholly or in part within the boundaries of Blount County on the effective date of this amendment may not annex any territory within Blount County without the approval of a majority vote of the qualified electors of Blount County voting at a referendum election on the issue of the annexation. The provisions of this amendment shall not apply to any municipality incorporated after the ratification of the amendment that lies entirely within the boundaries of Blount County. This amendment does not apply to any territory annexed within Blount County by a municipality prior to the effective date of this amendment. The Legislature may pass local or general acts to supplement this amendment provided the acts do not contravene this amendment.