Section 16. Notwithstanding any other provisions of this chapter, if a corporation organized under section three has carried out its obligations and performed its duties as imposed by this chapter for fifteen years from the date of its organization and for such further time any period of extension granted pursuant to section ten shall be in effect to the satisfaction of the housing board, all as evidenced by a certificate transmitted by the board to the commissioner of revenue, it shall thereafter have all of the rights and privileges of a corporation organized under or subject to chapter one hundred and fifty-six and be subject to all of the obligations and duties of such a corporation, and such corporation and its stockholders shall thereafter be free from all of the special limitations, restrictions, obligations and duties imposed upon corporations organized under section three and the stockholders thereof.