The big question now is: Who will try to buy it? And whom would the Citizens approve as a buyer? Anshe Chung is therefore out of the running unless she buys off the entire town first. Let's go with what we know first.
Governor Shang's not interested.
Lunar-san, the Seneschelf and Herr Baron seem to have their hands full.
Dr. Obolensky seemed to have grand designs on New Babbage before his base collapsed, but he has apparently given up on the World Domination career path.
I'm not in the market for an island nation at the moment. And Marcus already has one.
A few names come to mind, but even then they'd be longshots:
Dr. Malegatto Alter - Come on, who wouldn't vote for teh Evil Tiny Kitteh?
Emperor Steelcobra Calamari - He's expansionist, by his own admission.
Agent Iason Hassanov - He'd make the trains run on time. Isn't he a train himself? More like a tank I think.
Spring Heeled Jack - He was a Babbager but no one's seen him in ages. In his timehopping backstory he was at one time the ruler of a steampowered nation. I always assumed it was Babbage.