Either you need a crazy thermal solution, or it must be way less thermally dense than smaller chips can be. And is it really that much of an advantage to stay on chip compared to going through a PCB, if distances are crazy?
I'm surprised this hasn't been done before; a monolithic wafer can achieve denser interconnects, and is arguably simpler than a multi-chip module.
On the other hand, multi-chip modules can combine the working chips in low-yield wafers, whereas a monolithic wafer would likely contain many failed blocks, uselessly taking up space / distancing the working chips.
Cooling isn't really a problem, as the TDP scales with area as in other chips. Water cooling or heat pipes can transport the heat away to a large heat sink. 3D / die-stacked chips have a harder cooling problem, potentially requiring something like an intra-chip circulatory system.
It does seem to enable interconnect with impressive latency and bandwidth. It probably is worth it considering both Google and Nvidia systems are interconnect-limited.
Either you need a crazy thermal solution, or it must be way less thermally dense than smaller chips can be. And is it really that much of an advantage to stay on chip compared to going through a PCB, if distances are crazy?