Intel had some heat problems when they tried this. The FPGAs weren't able to use their heat budget dynamically, and as a result, the whole SiP had bad performance.

AMD chiplets?

Yes this was my thought too, does heat from a separate chiplet really effect the other cores maybe a cm away? I don’t know...

Possible, but I suspect heat and area would be problems, at least for the CPUs.

A smaller AMD core could be supplied as a hard core on the Xilinx part but would that really be worth it?

It would be an interesting to get a cpu, gpu and fpga in one package. ML abstractions could be sent to the most sensible implementation. Maybe handheld mobile SDR transceivers could benefit from such an arrangement too. AMD has had some great low power parts and maybe they’ll drive for that here?

“Lowmpower” is not what comes to mind when I think “FPGA”.