Disincorporation shall not impair the obligation of any contract. If any franchise lawfully granted has not expired at the time of disincorporation, the disincorporation does not impair any right thereunder and does not imply any authority to interfere therewith to any greater extent than the city or town might have, if it had remained incorporated.

Obligations of contract shall not be impaired: State Constitution Art. 1 s 23.