last mile. The implication is that public pol- icy may be better served if Congress and the FCC were to reject network neutrality in favor of a network diversity principle that would allow networks to differentiate their services in precisely this manner. It is possible that such network diversity may take some time to emerge. Indeed, the seminal analyses of production differ- entiation recognize that the initial industry entrants may well prefer to offer pro- ducts that are quite similar (Hotelling 1929). As entry increases, providers should begin to find it profitable to pursue more targeted strategies (Steiner 1952). Thus, policymakers should avoid imposing regulations that would foreclose the emer- gence of network diversity even in the absence of the imminent arrival of a new entrant offering differentiated services. Humility about policymakers' ability to 21 Shapiro (1999, p. 678) notes how exclusivity "can serve to differentiate products and net- works." 22 Interestingly, the NFL's decision to start its own cable network may alter the current situation. Networks in Telecommunications predict which business models will prove successful further underscores the impor- tance of leaving this possibility open. In summary, the complexity of the interface, the increasing heterogeneity of end users' demands, and the pace of technological change are reducing the util- ity of the regulatory tools upon which policymakers have traditionally relied to manage interconnection, nondiscrimination, rate regulation, and standardization. It is particularly telling that two noted scholars of network industries not noted for deregulatory views have suggested that access regimes have proven SO unworkable that they should be abandoned (Joskow and Noll 1999). 3. Network Diversity and Dynamic Efficiency Not only would network neutrality threaten to reduce static efficiency; it also poses a serious risk to dynamic efficiency. The literature exploring the impact of mandating interconnection on dynamic efficiency in the context of anti