512C totally doubt this with the meager density gains they have to make the package significantly larger 384C seems possible
I think it will come down to competition. If there is no reasonable competition to Zen 6 in DC, then I agree, they will not increase core count (maybe frequency, maybe a little more transistors per core).
Well there is speculation - Something based on known information.
As usual, your attempt to define the world according to your own definition is .... wrong.
Dictionary Definition
Speculation: "
The forming of a theory or conjecture without firm evidence."
Not only are you wrong, you are 180 degrees wrong. Speculation, by its very definition, is a theory that has no proof or "known information".
Now, your "speculation" on why we won't see core counts go out the ceiling (RAM per core, or bandwidth per core) may have merit in some situations, but not all.
A productive speculation would be to outline what instances more cores without more RAM or more bandwidth is useful.
Also, as others have done, outlining the cost to AMD to increase core count on A14/A16 is an interesting topic for speculation .... and which node Zen 7 might be on in the future.
I don't consider 512 cores per socket to be out of the realm of possibility for AMD.... although as things sit today, it may well be outside the realm of financial good sense.