The charter shall provide for the orderly transition from a county form of government to a city form, for the assumption by the new city of the debt and contractual obligations of the former county and of all towns formerly located therein, and for the transfer of all assets from such county and towns to the new city. The city charter shall recognize any townships which may be created pursuant to § 15.2-3916, and where such townships are created, they shall assume the assets and debts of the towns they succeed. However, the city charter shall provide that all or part of the revenues of a township, the services it performs, its facilities, other assets, and debts may be transferred to the city by agreement of the governing bodies. The provisions of the charter with respect to elected officials shall conform to the applicable requirements of the Constitution of Virginia. The charter may also provide that the new city may continue any agreements or arrangements undertaken under other provisions of law for the joint support of officials, facilities, and services that exist on the effective date of the city charter. Such charter shall become effective on July 1 in the year of enactment by the General Assembly.