Rockstar today announced that Red Dead Redemption 2 is coming out on PC on November 5th, 2019.
Red Dead Redemption 2 will first launch on Epic Games Store, Greenman Gaming, Humble Store and Gamestop. We assume the Epic Games Store would launch a Rockstar Games Launcher client version of the game, and the resellers would sell keys for the Rockstar Games Launcher edition of the game. It will also be a launch title for Stadia in November.
And a Steam release? This is announced for some time in December. Presumably this will launch a Rockstar Games Launcher client version of the game as well, as it now does with Grand Theft Auto V and other Rockstar titles.