(1) A new trustee or new trustees may be substituted for the original trustee or trustees of trusteed assets in the event of a vacancy or for other proper cause. Any substitution is subject to the commissioner's approval.
(2) If the trustees of any trusteed assets are individuals and if the number of trustees is reduced to less than three by death, resignation, or otherwise, the commissioner shall require that there be substituted for the trustees a bank or trust company in this state approved by the commissioner.