Just how ambitious is Smiley's proposal here? Well, when he talks about gaining control over interdimensional portal activity in Tal Sharnis, keep in mind that Tal Sharnis is currently the only significant human population center on the Endless Plateau. This means that the only kind of foreign trade that goes on in Tal Sharnis is trade with other universes, which requires the use of interdimensional portals... and without foreign trade, Tal Sharnis isn't self-sustaining.