It would be very realistic for Dior officials to court Hedi Slimane to make a return to the house, even though I guess that would potentially make his return in menswear a bit unexciting since they would likely continue with his existing winning formula there. Nonetheless, Slimane is well-known for having womenswear ambitions and was likely waiting with patience for a major job opportunity like this (or at YSL) to surface. Slimane is the best bet for sellable, modern tailoring and sportswear - I wonder, though, if his sensibilities would be well-suited for proper haute couture as one expects from a house like Dior? It is hard to imagine a Slimane evening gown at the Oscars only one year in advance from now, no?
I could on the other hand likely see the Rodarte sisters filling the womenswear niche without difficulty - they have a very distinct aesthetic language and would be one of the few young designers capable to do couture. As an independent design house, they also succeeded to establish their name among Hollywood's a-list celebrities, with Reese Witherspoon, Natalie Portman etc. all having worn their distinct evening dresses.
Another name I would find likely as a candidate for an interview would be Alexis Mabille - he's a natie frenchman who's worked with both Slimane and Galliano at Dior and he is doing both men's and womenswear independently, as well as a women's couture collection. I am sure he still has ties with the company and that the officials would rather consider a younger, easier to control creator over nominating a star designer with extravagant expectations on salary and control over the direction of the house.