In the global market, returning those addresses won't help at all.
Currently, the only reason the American registry still has any IP addresses left, is because their pool was separated from the emerging markets in Asia. As such, if IANA would start extracting IP address as suggested, the global market would eat it up faster than IANA could collect them. It would only "work" if IANA gave all the addresses exclusively to the American pool, working towards a local Internet rather than global.
Currently, the only reason the American registry still has any IP addresses left, is because their pool was separated from the emerging markets in Asia. As such, if IANA would start extracting IP address as suggested, the global market would eat it up faster than IANA could collect them. It would only "work" if IANA gave all the addresses exclusively to the American pool, working towards a local Internet rather than global.