RADIO scion John R. Gambling is returning to WOR-AM, Donna Hanover will leave, and Mayor Bloomberg will bring his weekly call-in show to the station.

That’s the scenario radio-industry sources say will be announced tomorrow, when WOR officials hold a noon news conference.

Multiple sources insist that Gambling, the third generation of the Gambling radio dynasty whose association with WOR dates back to 1925, is headed back to WOR, the station that dropped him as its morning-show host in 2000.

Gambling has been without a job since March, when talk rival WABC-AM discontinued his mid-morning air shift and replaced him with Curtis Sliwa.