I'd love to see an M# Mac Pro that costs $3,000 less than the Intel version. Given how much Xeons and Intel chipsets cost, this doesn't seem impossible. Apple being Apple, I don't think that's what will happen, but it will be interesting to see. If they release a new Intel Mac Pro and a new Apple Silicon Mac Pro, expect the Apple Silicon version to be cheaper, as part of the statement they're making here. How much cheaper...we will see.
Regarding GPU, it will be interesting to see if Apple decides to make a powerful discrete GPU, or does the work to let existing AMD or Nvidia (but let's be honest, it'll just be AMD) GPUs run on an Apple Silicon Mac. If they can come even somewhat close to the current top-end AMD GPUs, or let us run the standard ones, that will be good enough to me.
I'd be happy with the current form factor or a smaller one, as long as we can cram them full of storage, RAM, and PCIe cards. Be interesting to see how Apple handles thunderbolt and PCIe lanes on the Apple Silicon Mac Pro. Unified memory would be okay with me if we could still get 64+ GB at a price that isn't extortionate. Detached memory would be even better.
If there's one mac product line which is more likely to have both new Apple Silicon and Intel versions existing concurrently for a longer period of time, it would be this one. It would seem that the current design gives them lots of flexibility and headroom to run either/or designs inside.
A design with both architectures inside would be pretty cool, but we'll never get a cheaper one that way. I think I'm already prepared to switch to Apple Silicon if they can maintain the performance advantage on the high end, given how well Rosetta 2 seems to run.