I was thinking the same thing. There will be practically no reason for AMD to sell a 6c part, especially since they can push budget buyers on to what's left of AM4 for 6-12 months. Or they can cover it with AM5 Rembrandt. Or both. Regardless I do not think the baseline Raphael 8c part will be $500.
It's what intel has been doing for a while already.
Release K or X parts early, have a nice round of reviews and then 6months later the mainstream parts and motherboards are released.
It's a fairly good schedule for the companies. Halo parts to win margins, garner a lot of press and don't need to be in high supply.
As you said am4 is a solid platform with a new top to bottom cpu product stack and it'll be dependant on how much amd wants to push people to am5.
For me it's if the 7600x is either $250 or $300 covering that range.
There's also the option of bumping core numbers again and having 8core raph at 300ish and 8core remb closer to 200.