Requiring the incumbent mono/duopolistic last-mile ISPs to lease their lines may improve the situation, but I'm not as sure as Sam Altman that it would bring about real competition, because of the difficulties inherent in enforcing "fair, transparent leasing." Incumbents surely would find lots of clever ways to game any leasing scheme imposed by the FCC while technically "complying" with it.
I expect it would be better for US consumers than the status quo, though.