The article doesn't note this, but wafer scale integration is a very old idea. We discussed it at Inmos back in the day, since often the systems we built essentially consisted of many CPU die sliced out of the wafer, bonded into a package, then tiled onto a PCB[1]. But there are...issues: cooling for one. Iann Barron joked that you could make a toaster from two WSI wafers running full-tilt.
[1] https://twitter.com/tnmoc/status/429638751904878592