Eighteen months after the flamboyant Briton was sacked by Dior over a racist outburst in a Paris bar, Galliano's name has been linked -- among others -- to the revival of Elsa Schiaparelli, the house of the late Italian designer.
Diego Della Valle, head of the Italian leather goods company Tod's, has acquired the house along with a new venue on Paris' Place Vendome, and is to announce the name of its new artistic director at the start of October.
But in the meantime all eyes are on the return of Slimane, who retired from fashion five years ago and who along with Galliano's recently-named successor at Dior, Raf Simons, is considered among the top designers of his generation.
"Slimane and Simons bring a powerful new energy that makes Paris stronger on the creative scene," said Serge Carreira, professor at Sciences-Po university.
Both in their forties, the two share a pared-down aesthetic set to inject a strong new identity to the classic houses they are joining and Slimane has already changed the name of his ready-to-wear line to Saint-Laurent Paris.
"We hadn't seen anything like this since the arrival of Galliano at Dior and Alexander McQueen at Givenchy in the mid-90s," Didier Grumbach, head of the French Couture Federation, said of the excitement at their arrival.
"Paris is firmly at the centre of the map."
The double debut of Slimane and Simons -- who gave a taste of things to come with a well-received haute couture collection for Dior this summer -- is also being billed as a duel between two giants of the industry.
On the one hand Dior, owned by Bernard Arnault the head of the LVMH luxury conglomerate, and on the other Saint Laurent, part of the PPR empire of Francois-Henri Pinault.
"Both are talented people -- and there is room for everyone," was Grumbach's diplomatic response to the suggestion of a contest.
For Carreira, both designers share a taste for pure lines and fine materials, in tune with their times.
"This isn't the minimalism of the 80s or 90s," that of the Japanese generation, or Helmut Lang, he said.
For Jean-Jacques Picart, an influential luxury sector consultant, they share an aesthetic best defined as "essentialist with an austere edge".
He praised Simons' couture line for Dior as "modern, rooted in wearabilty and decency."
Born to a Tunisian father and Italian mother, Slimane is seen as having revolutionised the way men dress during his stint at Christian Dior, from 2000 and 2007, making Dior Homme each season's must-see show.
His distinctive skinny suits and tight low trousers found imitators not just in fashion but in the rock sphere that so fascinates him.
At YSL, his challenge will be "play with the rich and multiform universe of Yves Saint Laurent, to make his themes relevant to today's world," whether his masculine-feminine ambiguity, his use of black and colour, said Carreira.
Chanel, Balenciaga, Jean Paul Gaultier, Lanvin, Dries Van Noten, Louis Vuitton and Givenchy are just a handful of the 90 plus houses which will send out their ready-to-wear looks for spring-summer from September 25 to October 3, on the heels of the New York, London and Milan fashion collections.