Apple Neural Engine is a thing already, with support for multiply-accumulate on INT8 and FP16. AI inference frameworks need to add support for it.
> this setup can support up to 4 Mac devices because each Mac must be connected to every other Mac!!
Do you really need a fully connected mesh? Doesn't Thunderbolt just show up as a network connection that RDMA is ran on top of?
If you daisy chain four nodes, then traffic between nodes #1 and #4 eat up all of nodes #2 and #3's bandwidth, and you eat a big latency penalty. So, absent a switch, the fully connected mesh is the only way to have fast access to all the memory.
If you have 3 links per box, then you can set up 8 nodes with a max distance of 2 hops and an average distance of 1.57 hops. That's not too bad. It's pretty close to having 2 links each to a big switch.
Or, Apple could pay for the engineers to add it.