Any referenda establishing a regional school district before June 24, 1969, which by the terms of the question presented in such referenda established a regional school district to provide educational programs for kindergarten through grade twelve, shall be deemed to have empowered such district to provide for the member towns any program under the general supervision and control of the State Board of Education. In such cases, the town board of education in each member town is dissolved when the regional board of education assumes the direction of all such programs in the member towns, but in no case later than two years from the date of the referenda establishing such regional school district.