Well, we didn’t see this one coming: After three-and-a-half years as Christian Dior’s artistic director of women’s haute couture, ready-to-wear, and accessory collections, Raf Simons is parting ways with one of the most storied French fashion houses around. Simons “reached this decision for personal reasons,” according to a statement reported in WWD . Surprisingly, we won’t even be getting a final glimpse at Simons’ critically acclaimed work for Dior. Usually there’s one last catwalk hurrah after a designer decamps, but Simons’ spring 2016 collection shown in Paris earlier this month will be his last for the label.“It is a decision based entirely and equally on my desire to focus on other interests in my life, including my own brand, and the passions that drive me outside my work,” Simons said in the statement. “Christian Dior is an extraordinary company, and it has been an immense privilege to write a few pages of this magnificent book.”Simons and Dior apparently couldn’t reach an agreement about the designer’s contract, though the split is amicable, sources told WWD. Simons arrived at Dior in the wake of another unanticipated departure: John Galliano was booted out in 2011 following his anti-Semitic remarks at a Paris cafe, and Galliano’s right-hand man, Bill Gaytten, filled in for a few months before Simons’ arrival in 2012 Reactions on Twitter to the unexpected news ranged from the matter of fact to the critical ( were Simons' concepts too avant-garde to sell ?) and the sort-of humorous . There’s no word yet on Simons’ successor, but this is the kind of move that will kick off a very spirited guessing game in the industry. The magnitude of the Dior name coupled with its strong couture heritage (not to mention the brand’s strong sales under Simons’ lead) puts a lot of weight on whoever takes Simons’ place.Givenchy’s Riccardo Tisci is the front-runner, per WWD; it could make sense for the new head of Dior’s designs to be a talent already working for one of Dior parent company LVMH’s brands. Other names tossed into the ring include Jonathan Anderson, who is already the creative director at a label owned by LVMH (Loewe), as well as Lanvin’s Alber Elbaz, Céline's Phoebe Philo, and Proenza Schouler's Jack McCollough and Lazaro Hernandez. So, who do you think can suitably fill Simons’ shoes?