Designing for competition is an important consideration for the design of future Internet architectures. Network architects should systematically consider the loci of competition in any proposed network architecture. To be economically sustainable, network architectures should encourage competition within each locus, anticipate and manage the interactions between the loci, and be adaptable to evolution in the loci. Given the longevity of network architectures relative to network technologies and applications, it is important to ensure that competition is not unnecessarily foreclosed at any particular locus of competition.