If streets or utilities are not available at the boundary of a proposed subdivision, and if the City Planning Commission finds the extensions across undeveloped areas would not be warranted as a special assessment to the intervening properties or as a municipal expense until some future time, the developer may be required, prior to the approval of the final plat, to obtain necessary easements of rights-of-way and construct and pay for such extensions. Such improvements shall be available for connections by developers of adjoining land on a cost reimbursement basis in compliance with ordinances of the City.