Dual ported TCAM memory isn't getting faster and we've got to 1,000,000 prefixes in the internet and ipv6 are 4 times bigger. Memory speed is a real issue.
Dont mistake technical viability for economic viability.
We're on 8 as a mixture of fast and slow, hot and cool, on almost all personal devices now. I routinely buy Intel instruction racks with 16 per CPU construct, and a TB of memory. At one remove, chips seem to be fulfilling my mission but I am not in GPU/TPU land. Although I note, FPGA/GPU/TPU seems like where a lot of the mental energy goes these days.
VLSI is a black art. Quantum effects are close enough to magic I feel confident saying few people today understand VLSI. I know I don't, I barely understand virtual memory. I ache for the days when a zero pointer was a valid address on a pdp11