More precisely, we don't know how to aggregate 32 bit locators
any better than 64 bit locators.
Um. Yes we do. It is called CIDR. It is well understood and has the
minor advantage of being deployed. What we don't know how to do is
aggregate in the face of people refusing to aggregate for
'non-network-topologic' (e.g., economic, political, business, etc.)
reasons. One known and obvious way of doing this is by separating the
two and providing a mapping. Locators can then be re-arranged without
getting into non-network-topologic arguments.