All the speculative successors are very bad. Among them is former Congressman Scott Mc Innes of Colorado. He's as reactionary as the rest. Deputy Secretary Lynn Scarlett, now the Acting Secretary, is widely viewed as the power behind the throne. Her nickname is "Scarlett Letter", and widely viewed as Norton's likely successor. The good news is that the nomination hearings will be very interesting.
Norton may have won accolades for being a nice smile behind reactionary politics, but she was not without controversy. She ignored warnings from her own Inspector General and others that employee disciplinary procedures throughout Interior lack "Due Process" for the charged employee, leading to "Hatchet People" meting out unfair and political discipline. This kind of "Culture of fear" has prompted many good employees to leave government service, and may have been an element leading to the recent suicide of BLM Carrizo Plains Project Manager Marlene Braun.
Norton's former deputy Secretary, Steven Griles, was an oil industry lobbyist before and after his stint of public service at Interior. He never stopped serving his private industry employers. Mr. Griles has been implicated with the notorious ex-lobbyist Jack Abramoff in a gaming ripoff of Native American tribes, and this spreading investigatation may have been what prompted Norton's resignation.
Norton professes that she left on her own accord, on good standing. However, it is well known that bad press is always released on Friday afternoon, as her announcement was.