PCIe cards would indeed be useless for AI unless Apple supports third-party GPUs, but there are certainly some pro creators that would still prefer to have them

PCIe cards would indeed be useless for AI unless Apple supports third-party GPUs, but there are certainly some pro creators that would still prefer to have them. I myself work in large-template film/game scoring and while we all love our Mac Studios, they're usually housed in a Sonnet chassis so that we can continue to use PCIe cards. Had Apple kept them in parity with the Studio w/r/t CPU and RAM, the rack-mount version of the Pro would've been a no-brainer.