Yep. It’s official. The IPv4 space allocated to ARIN for North America has been officially exhausted:
On 24 September 2015, ARIN issued the final IPv4 addresses in its free pool. ARIN will continue to process and approve requests for IPv4 address blocks. Those approved requests may be fulfilled via the Wait List for Unmet IPv4 Requests, or through the IPv4 Transfer Market. […]In the future, any IPv4 address space that ARIN receives from IANA, or recovers from revocations or returns from organizations, will be used to satisfy approved requests on the Waiting List for Unmet Requests. If we are able to fully satisfy all of the requests on the waiting list, any remaining IPv4 addresses would be placed into the ARIN free pool of IPv4 addresses to satisfy future requests.
See: ARIN Website
Fat chance of anyone returning any “unused” space. It’s a hoarder/squatter’s market now.