The territory of the non-high school district or unit district not maintaining a high school in existence on January 1, 1950 of any county having a population of 500,000 or less shall be automatically eliminated from the non-high school district or unit district, unless (1) the non-high school territory is adjacent to a district created by a special Act whose boundaries are required by such Act to be coterminous with some city or village or to a district maintaining grades 1 through 12 and (2) has children in such territory who customarily attend the high school of such district and (3) has no school district operating grades 9 through 12 to which such territory could be annexed without impairing the educational opportunities of the children of such territory and in such case the territory shall remain non-high school territory.
     Any such non-high school district including any unit district not maintaining a high school pursuant to the provisions of this Section shall pay tuition for high school students at a rate to be mutually agreed by the boards of education of each district affected.
     When territory is eliminated from a non-high school district or unit district not maintaining a high school it shall be annexed by the county board of school trustees as provided in Section 7-27 of this Code (now repealed).
     Any non-high school district affected by such elimination and annexation may continue to exercise all previously conferred and existing powers pending final administrative or judicial affirmance thereof.