I rather hope it is not Lopatkina. Her recent lapses of style and taste in her own performances make me wonder if her directorial style would be any preferable to Vaziev's.
Unfortunately, due to the mutual respect and professional relationship that Gergiev and Lopatkina have, she will probably be at the top of his short list. She was Dudinskaya's student, and Dudinskaya was Vaganova's student, so there's a direct lineage here. On the other hand, Gergiev has never been a balletomane, he is an opera man, nor does he understand the needs of the ballet, either musically, (the Lopatkina "Swan Lake" dvd and other CDs), or aesthetically, (failure to build the new theatre, and the rehearsal "space" the ballet's been accorded). Also
under Gergiev, the Orchestra received a new concert hall. Here's another example: Do you remember the infamous Shostakovich marathon at the London Coliseum two years ago?
IMO Uliana couldn't do worse than Vaziev, and neither could Altynai. Even Gennady Selyutski would be an excellent choice. Consider this: The number of eligible choreographers can be counted on one hand right now; and most of them are already committed. Gergiev will need to start looking as soon as possible and make a selection - even if it's an interim selection.