Christian,
Paying can be done in many way, from the "consortium" which you suggest to
some fees to a service company that operates the ACID. In fact, the major
roadblock here is the intrisic monopoly -- at first sight, there can only
be one ACID for a given aggregate. This may trigger all sorts of
regulatory questions.
It had been pointed out several times before that hierarchical routing
has an *inherently* monopolistic aspect - it ties an organization
whose addresses have to be aggregated with the organization that
aggregates these addresses (aggregator).
Yakov.