If that is so, would it be entirely to decrease search space for layout algorithms? I believe there isn't anything in the fabrication process that couldn't model diagonals.
I could see that square packing is more simple, but by shifting elements per row I don't see why it couldn't propagate at odd angles.
That's also my assumption. Place and route has to work out an NP hard problem on billions of wires.
Are the next generation of Cerebras chips designed by the current generation? Maybe it won't be recognizable as a particular layout but rather a chaotic but functional vibe layout.