Rainbow Six Quarantine has been planned for launch before April 2020.
CEO of Ubisoft Yves Guillemot has stated that the game will be due sometime before the end of the fiscal year for Ubisoft. Knowing their schedule, that must be before the end of March 2020. Ubisoft has a history of releasing games around the start of the year, so this makes sense.
They’ll also be pushing out Watch Dogs Legion and Gods and Monsters around the same time, so this isn’t anything too out of the question. Rainbow Six Quarantine will be the newest standalone title with 3 player co-op vs. the “zombies” and has characters from Rainbow Six Siege.
The game should be very similar to the Outbreak game mode that was in RSS last year. Now they turned that into a standalone title.