If it appears to the Commission (on the basis of statements claiming exemption or otherwise) that a substantial question of law or fact exists as to whether any holding company claiming exemption under § 250.2, § 250.3, § 250.4, § 250.5, or § 250.10 or any other section now or hereafter in force pursuant to section 3(a) of the Act exempting any class of holding companies from the registration requirements of the act, is within the exemption afforded by any such section, or if it appears that any question exists as to whether the exemption of any such company may be detrimental to the public interest or the interest of investors or consumers, the Commission may notify such holding company to that effect by registered mail. Thirty days after such notification, such exemption shall terminate, without prejudice to the right of such holding company to file an application for an order granting such an exemption pursuant to any applicable section of the act, and without prejudice to any temporary exemption provided for by the act if such application is filed in good faith.