The existence of USB-C and Thunderbolt 3 means that the Mac Pro, as it is right now, might not be very necessary. Processors and RAM are important, of course,

The existence of USB-C and Thunderbolt 3 means that the Mac Pro, as it is right now, might not be very necessary. Processors and RAM are important, of course, if you're doing intensive work, but things like GPUs could be attached separately via Thunderbolt 3. I could see AMD creating a pro-level FirePro external TB3 "card", a box like an external hard drive that you just plug in via TB3 and off you go. Apparently only one of the FirePro GPUs on the Mac Pro is hooked up in such a way as to contribute towards graphics performance, with the other being solely for compute; an external box designed specifically to hold a FirePro chip and associated hardware (VRAM, VMU, etc) could be styled, cooled, and shaped differently, and could provide a simple add-on for people who want parallel computation. In other words, we could use TB3 to add on FirePro computation the way we use USB to add on hard drives. With that kind of philosophy, the Mac Pro could be cheaper and easier to build, more expandable and not less, and appeal to more people. If I could order what was effectively a Mac Mini but with 32 GB of RAM and a Xeon or high-end desktop i7, I would buy ten of them tomorrow, and for people who want to do things like hardware-accelerated computation or transcoding they could buy add-ons that would do that work for them.