I hope Apple does end up moving to HBM. Unified memory has been a huge godsend, but the low memory bandwidth is just such a killer. Even/especially on M5, where the available compute is starting to starve incredibly badly on ML workloads.
Apple is reportedly considering skipping the higher-end M6 chips altogether, which could potentially give enough time for higher-end M7 (in over a year) to use HBM
Who cares? If high-end M7 chips come out with HBM and actually compete with GPUs from this decade I'll be really happy. I'm also hoping for more than 128GB of unified memory in a laptop.
