From my reading of the Rekhter & Li CIDR paper I believe the allocation strategy is to assign blocks to immediate providers ("retail" or "access"?) and that those providers get their allocation from the regional NIC, which for this purpose would be the InterNic acting as
Scott, I don't think network service providers should take address blocks hierarchically related to allocations from other service providers in the US. I don't believe this is an issue of multi homing, it is simply the issue of minimizing the probability of customers having to change their addresses. If an access provider changes its "long haul" provider it would be nice if there were no pressure for the customers of the "access" provider to change addresses. the NIC for the U.S.
From a U.S. point of view I could see carving the U.S. up into a few regions (probably a max of 4) where immediate/access/retail providers for a restricted region (provider XXX is a dialup provider for the NY area) get their allocation out of those geographically defined blocks rather than a generic undifferentiated US block.
cheers, peter