Any provider desiring to sell or transfer ownership of a continuing-care facility shall notify the department 30 days in advance of the completion of such sale or transfer. The commissioner may revoke, after notice and hearing, upon written findings of fact, the certificate of authority of any provider based upon a substantial change in control or ownership of such provider, which change is found not to be in the best interests of the residents of the facility or facilities owned or controlled by the provider such that the facility or facilities is in the imminent danger of becoming insolvent or that the care of present or prospective residents is threatened thereby.