After contacting RCProds, the studio doesn't confirm such a project for Hans Zimmer nor for collaborators.
The french singer Patricia KAAS plans to go on scene for a 2hours30 minutes show, "Patricia KAAS Chante PIAF"(Patricia Kaas sings Piaf) dedicated to Edith PIAF. Patricia KAAS describes this show as something grandiose with a particularly well staged, and would like to work with a film composer, preferably with Hans ZIMMER. Approaching 50 years of the death of "La môme", the singer is working on a cover songs album, wich will be sold in 45 countries and a mondial tour dedicated to Mrs. PIAF, beginning in Paris at renowned Bruno COQUATRIX' OLYMPIA from february the 26th. to March the 3rd. 2013. Hans ZIMMER already worked on Edith PIAF' song "Je Ne Regrette Rien" in his soundtrack "Inception" (see exemple below). Here's the french interview where Patricia KAAS speaks from this upcoming show (around 20th. minute).