> with perhaps 32GB of onboard memory and the external RAM being used as swap?
I wouldn't be surprised if Apple was working on some ways to optimize swap so that SSDs can fill the roll of "external ram." At this point, PCI Express has the theoretical bandwidth to compete with DDR5, but it can't handle anywhere near the number to transactions. But I bet with some clever OS-level tricks, they could give performance that's good enough for most background applications.
Apple's still working with the same NAND flash memory as everyone else, so there's little opportunity for them to do anything particularly clever at the low level.
But even looking at commodity hardware, high-end SSDs are already capable of handling a comparable number 4kB random reads per second to the number of context switches/page faults a CPU core can handle in the same second. The huge latency disparity is the problem: the SSD would prefer you request 4kB pages dozens at a time, but a software thread can only fault on one page access at a time. Using a larger page size than 4kB will get you much better throughput out of a SSD. On the OS side, swapping out a large number of pages when the active application changes can make good use of SSD bandwidth, but when a single application starts spilling into swap space, you're still fundamentally screwed on the performance front.
I wouldn't be surprised if Apple was working on some ways to optimize swap so that SSDs can fill the roll of "external ram." At this point, PCI Express has the theoretical bandwidth to compete with DDR5, but it can't handle anywhere near the number to transactions. But I bet with some clever OS-level tricks, they could give performance that's good enough for most background applications.