1. Potential Alliances With Other Foes
BBCWe've seen how the Rani is a formidable opponent in her own right; her ambition and schemes propel her to heights that most villains never achieve. Imagine then, what sort of havoc she could wreak when allied with another villain. Granted, we've already seen an alliance between her and the Master (and how it didn't really end all that well), but if the Rani chose to create an alliance with someone she actually respected and admired, the results could be catastrophic. It's something of a stretch to have the Rani willingly team up with another villain; she's always been something of a loner and cares only about her experiments. But if she decided to work with a similarly-minded villain - say, for instance, Davros - her intelligence and determination could give the bad guys precisely the advantage they need to win the day. It certainly would make things more complicated for the Doctor!
What are your thoughts? Do you think the Rani should return? Who would you like to see play her? Let us know in the comments!