Of course, but generations exists along each other for a while. I'm not suggesting a 5600X3D, a pundit of some sorts did and it got me thinking. Like
@The Mass Shooter Ron Soye said, even since Zen 2 the potential for 3D cache was there. Jumping to a new node/process(as far as I know) and socket for Zen 4 doesn't mean that they will immediately stop production of 5000 series, the 5000's is still an upgrade path for older Ryzen users.
It was meant as a topic of general discussion because, like you say, the idea seemed odd at this point in time. What function would a 5600X3D fill at this point? In my opinion it would be gaming, but it won't be overclockable so the RGB enthusiast market would probably shrink away. It would probably priced around the 5800X and who knows how it would do at productivity tasks that utilizes all cores compared to the former. But like I said, it was just an article that said AMD should do it and to reiterate: I could not figure out why they should.