It probably won't permanently be called Xena (http://en.wikipedia.org/wiki/2003_UB313#Name). Basically, planets have to be named after mythological things, preferably from Greco-Roman mythology. "Persephone" seems appropriate. But there's an asteroid named Persephone already (and in fact, there are asteroids named after basically all the Greek and Roman mythological characters) so they might end up using a name from another mythology. "Hades" is apparently free, though.