Apple has promised the next Mac Pro, due during 2019, would be modular without explaining what they mean. As I've been documenting on TechSparx, Apple's current design style is unrepairable unmodifiable machines. The sort of Pro users who would want a Mac Pro, however, want upgradeability for example to swap in new graphics cards or max out the memory. In short, the design ethos Apple should follow is precisely the 2009/2010 Mac Pro design.