The only thing I could think of on the question of Apple Silicon and Metal is that they think they could still split out the cold neurons to the CPU/Accelerate

The only thing I could think of on the question of Apple Silicon and Metal is that they think they could still split out the cold neurons to the CPU/Accelerate and the hot ones on the GPU and utilize both. The speedup is likely less if there is already no copying of data between GPU/CPU and using the unified memory. Still, it would be great if you could use even more of the capabilities of the chip simultaneously. In order to avoid thermal throttling they should use the efficiency cores only (I think this is what game mode does).