In any case in which, in the opinion of the Comptroller of the Currency, it would be to the advantage of the depositors and unsecured creditors of any national banking association whose business has been closed, for such association to resume business upon the retention by the association, for a reasonable period to be prescribed by the Comptroller, of all or any part of its deposits, the Comptroller is authorized, in his discretion, to permit the association to resume business if depositors and unsecured creditors of the association representing at least 75 per centum of its total deposit and unsecured credit liabilities consent in writing to such retention of deposits. Nothing in this section shall be construed to affect in any manner any powers of the Comptroller under the provisions of law in force on June 16, 1933, with respect to the reorganization of national banking associations.