The Atlantic City Organization as of the end of Season 3 consists of Nucky as Boss, and Eli, his younger brother, as his chief lieutenant, now that Owen has been killed. Eddie Kessler remains in the hospital following being shot, and it seems Mickey has betrayed Nucky to Rothstein.
Because of Chalky's loyalty to Nucky, and serving him faithfully through the Masseria/Rosetty business, now has permission to open his own club on the Boardwalk.