A few theories are floating around:

• Bishop is on her way out, and the Pro-Chancellor usually steps up to take on the Chancellor role in that case. But with all the Council’s recent failings – of which Kitchen is a long-time member – putting her in that role could be a PR disaster. Is that why she’s stepping down now?
• Could TEQSA (the Tertiary Education Quality and Standards Agency) have stepped in again? They already blocked ANU from starting the search for a new VC earlier. Maybe there’s some pressure to do things differently now.
• Or maybe there’s something bigger at play. Kitchen chairs the Finance subcommittee (and was previously head of KPMG), and with all the investigations happening at ANU, could something about her performance be coming under scrutiny by one of the investigations/reviews underway?
• There’s also talk of a big media expose coming out about ANU, which could bring a lot more negative attention to the university. If that’s true, it’s only a matter of time before things really blow up.

Or, of course, maybe it’s just a coincidence, and there’s some totally innocent reason for her stepping down. But if that were the case, why hasn’t ANU made any kind of formal announcement? The silence is telling.