I think the open question about the Mac Pro is the expandability. The trash can Mac Pro didn't do well and they went back with something with expansion slots. Is it worth it to Apple to build out and support everything necessary on the M1 platform for one low-margin line of computers? We'll find out in the next year.

Even the 27" iMac has a 128 GB RAM SKU, so they're going to need to build a chip supporting external RAM regardless. External PCIe support already exists thanks to thunderbolt. So the architecture will be there, it'll just be a question of how expensive it is to scale up.

Gigacore

16GB should be enough for everyone

Until they publicly show they can make such a thing, there will be some scepticism

You realize Apple is designing against more advanced nodes than intel - and from where I stand intel has nothing competitive in small form factors

Why? Apple just demonstrated that they could do something that had previously been considered unrealistic. They've also been demonstrating massive annual performance gains for many years. For people who have been watching closely, they should have some credibility by now.