(b) Upon impairment of such surplus, the commissioner may revoke such certificate. Such revocation shall not render subject to contingent liability any policy then in force and for the remainder of the period for which the premium has theretofore been paid; but after such revocation no policy shall be issued or renewed without providing for contingent assessment liability of the subscriber.
(c) The commissioner shall not authorize a reciprocal insurer so to extinguish the contingent liability of any of its subscribers or in any of its policies to be issued, unless it qualifies to and does extinguish such liability of all its subscribers and in all such policies for all kinds of insurance transacted by it. Except, that if required by the laws of another state in which the insurer is transacting insurance as an authorized insurer, the insurer may issue policies providing for the contingent liability of such of its subscribers as may acquire such policies in such state, and need not extinguish the contingent liability applicable to policies theretofore in force in such state.
(d) No reciprocal insurer shall deliver or issue for delivery in this state assessable policies imposing a contingent liability upon subscribers, if such reciprocal insurer is issuing for delivery to subscribers in this or any other state nonassessable policies insuring risks of substantially the same hazard and class.