I wonder if the Mac Pro version of this will do a two-tiered thing, with 16GB on the chip, and then a bunch of slots for your slower, "external" memory modules— basically the Mac Fusion Drive of RAM, with an internal controller to manage moving stuff in and out of the low-latency area.

I could certainly also see them going all-in on the integrated architecture, but the possibilities are intriguing if they want a reasonable story for a workstation that goes up to 100s of GB (the current Mac Pro's top configuration is an eye-watering 1.5TB of RAM).