Except Rift-S isn't a new product line, it's just a refresh of an existing product (it's not even Rift-2). People already know what a Rift is: "it's that VR headset that requires an expensive computer"
While we're waiting for an announcement, how about some guesses as to when it arrives. I'm going to say it'll have an announcement soon and launch alongside or very soon after Quest. Erm, so I think that's late spring... end of April beginning of May.