During inference, most of the memory is read only.
Development systems for AI inference tend to be smaller by necessity. A DGX Spark, Station, a single B300 node... you'd work on something like that before deploying to a larger cluster. There's just nothing bigger than what you'd actually deploy to.
The KAIST professor discussed an HBF unit having a capacity of 512 GB and a 1.638 TBps bandwidth.
PCIe x8 GPU bandwidth is about 32GBbps, so HBF could be 50x PCIe bandwidth.