I've posted this mockup I made before. In another thread before ARM Macs. Basically the iMac G4 design with a much longer oblong base to handle the cooling needs of modern CPU and GPU. With an ultra high quality web cam based off iPhone back cameras. I'd also add Face ID but that isn't in the mockup.
The screen itself would be ranged from 24" to 35" 4K to 8K.
- CPU, RAM and storage would be user replaceable.
- Not sure about the card. Given the base would be much wider than the iMac G4. It might handle a style dual slot GPU laying sideways with internal connector going to the monitor and rear thunderbolt DisplayPort outputs.
- CPU wise. I'd be fine with Apple Silicon. If they made it and the RAM socketed on the desktop with various CPU options. Such as the M1 Max size but without the extra GPU cores and all the space filled with CPU cores. Allowing people to install a dedicated GPU from AMD or nVidia. Heck even an Apple one based off their GPU but scaled up to a dedicated card.
- I'd also want a second PCIe slot if Apple Silicon was used. To install something like an old Orange Micro card. Doing your choice of Intel or AMD CPU.
If we're talking about about PowerPC. I'd want the latest IBM Power designs scaled onto TSMC's processes. Updated with big and little cores. Making the fastest PowerPC CPU they can. Scaled to the thermals appropriate for laptops, dekstops and workstations.
All in ones would be based off the below iMac G4 mockup. The mini would be inspired by the LC I but scaled down. The workstation off the Quadra 900. An upgradeable consumer desktop off the IIcx or IIgs. I won't get into laptops as I don't feel like it. Besides upgradeable RAM and SSD.
The UI would be clean and simple influenced by Next and Classic Mac OS. Although I'd bring in some OS X influences like the sidebar and toolbar.