The Flight Deck crew would inform the cabin crew and passengers that due to a technical problem the aircraft was returning to its departure point, or somewhere close to it. I suspect that the pax would be informed that it was not a technical problem with the aircraft, rather it was with the ground ATC facilities. It would not be any form of "emergency", just and en-route diversion.
What do you mean about circling until a landing strip was opened? There are several airfields in Hawaii to which aircraft could divert - no big deal really.