I'll admit I haven't read the whole thread, so my apologies if someone has already floated this theory.... But I suspect this all has to do with the failure of Apple's "post-PC" philosophy—or more specifically, with the market's demonstrated lack of interest in an entirely post-PC world. I've noticed that nobody is using that term anymore at Apple.... Since the iPad Pro had relatively modest sales (not terrible, but not through the roof), Apple has had to re-think the whole post-PC mindset. So they're having to figure out how to gain ground (again) in a world that refuses to let go of the PC. This was obvious enough to pro users, but apparently not to Apple. I openly admit that I would love to be able to compose meaningfully on an iPad Pro, but I would still always have a MacBook Pro or Mac Pro for final production.
Also, there has been a significant rise of the so-called "prosumer" (a ridiculous f***ing term that never should have been coined), who are rapidly outgrowing their hardware. My guess is that Apple now recognizes that there is actually money to be made in converting those prosumers over to pros, if they do it right (i.e., make it scalable).
So, my guess about the "modular" approach is that they will be taking the idea very far indeed—as in, totally scalable modules of CPU (Intel and/or ARM), GPU, SSD, and perhaps even RAM (though this will probably be integrated into some kind of CPU module, for throughput). They may even enable some of these modules to be used with MacBook Pros, so that components of the "studio" rig can be taken on site. It's the only reason they'd need such a huge amount of time. Doing it this way, they'll be able to keep things up to date more effectively, and at less expense, and perhaps even at a more reasonable cost to the customer. I know everybody will scream about that last point, but Apple has never got it in neck about price as much as they did with the TB MacBook Pros. They're feeling it, even if they're not mentioning price as a sticking point. Will such a system ever be as cheap as a Hackintosh? Obviously not. But if it's entirely customizable, and entirely plug-and-play, with totally native macOS support, it will definitely sell. (And I'm saying this as someone who has built and run about 5 Hacks over the years... Including a laptop... which was hell... bought a TB MacBook Pro after 3 months. Ha! You can't replace the user experience of a MacBook Pro... Apple's laptops are just very, very well made. Sorry. Cue the customary MacRumors bitching and moaning.)
