> The commodity chip almost always caught up in the meantime at a lower cost.

This dynamic is dead now, thanks to the slowing down of Moore's Law. We're even seeing a resurgence of special-purpose hardwired accelerators in CPU's, because "dark silicon" (i.e. the practical death of Dennard scaling) opens up a lot of opportunity for hardware blocks that are only powered up rarely in a typical workload. That's not too different from what the Lisp machines did.