I'm pretty sure Verisign don't sell or release cc.com domains anymore (just like c.com domains). All the old ones are still there because they've been grandfathered (like q.com, x.com and z.com).
They likely see the colossal value and will likely hold them until one day putting them up for auction (if ICANN allows them to make exceptions and sell them for more than their ~$8 cap.