thunderbolt as it is today can't really fill those voids
Apple is a rug-puller. They pull the rug out so that people are forced to adapt. I'm sure there are some scenarios where Thunderbolt would fall down but not many and manufacturers would be fairly quick to adapt. Thunderbolt just puts a type of PCI on the outside, same as ExpressCard, it's up to manufacturers to do the rest just as they have with standard PCI.
I've noted on macrumors a few people use imacs for after effects work. The common complaint is that they get blazingly hot. Being within a few degrees of throttling or shutdown isn't really a good idea if it's going to run for hours. The problem is that lately that's what you get with Apple. They don't really design it with these uses in mind. You could play games over a macbook pro, but those fans will max out the entire time. Essentially they're not designed to be run at their full potential for longer periods of time. This is mostly hypothetical, but Apple's solutions break whenever your usage patterns don't line up with their design goals.
If you are maxing out your machine for hours at a time, you aren't using it as a workstation. It's clear Apple's movement is towards real-time. Motion and FCPX using the GPU to render and FCPX doing background rendering, both using OpenCL. That's the best way to go.
I'm in no way suggesting large computing resources (servers/workstations) are at present unnecessary, just that Apple doesn't have to accommodate that market. Apple doesn't even use their own servers in their own data centres. If you are a high resource user, you can buy a headless PC for the intensive tasks like video transcoding, rendering and so on and use the Mac for the real-time tasks. The cases where a Mac Pro can perform real-time tasks that the lower models can't are almost non-existant.
Somewhere down the page they reference a 16 core workstation. They've also mentioned rendering smaller projects on a single workstation in a couple of their videos.
"Although we got a powerful render farm here at Taylor James we aim to keep our render times as low as possible. With the flexibility of V-Ray you can easily tweak your render times. Normally we aim for 30 min per frame for an HD frame on a 16-core machine."
If you used a single 16-core machine to render a 30 second TV commercial, it would take:
30 min/frame x 30 frames/second x 30 seconds = 27,000 minutes = 18+ days.
It'll take 10 years before that is feasible using the iterative approach, probably longer if they target higher resolutions. Stills can be done on single machines and obviously more basic animation but these can be done on lower-end hardware too. The smartest way is to have an efficient workflow that allows full creative control and not having your deadline dependent on transistor count.
You can argue in favor of abandoning them, but not wanting to take on a leveraged solution isn't really the same thing as holding back progress.
I wouldn't say I'm entirely in favour of them abandoning them, I agree with your point about providing the right solutions but I absolutely believe they hold back progress. Necessity is the mother of invention and the Mac Pro tries to satisfy needs by offering raw power. It leads people to desperation for incremental performance when the desperation should be for better solutions. Do people really want to keep clinging onto the hope of a 40% speed bump every 2 years? It's slow torture.
What's the alternative you may ask? Just what you said, use the right solutions for the task. Get a render farm for rendering, get custom hardware for tasks that require it.
Better hardware means less animation would need to be done via proxy models with lower poly counts, meaning you'd have better feedback. I don't really care what the computer looks like. I care about design priorities, the point of a machine is to solve problems.
The iMac GPU is very fast so real-time animation doesn't suffer at all. While the iMac CPUs are 1/3 of the 12-core Pro, the GPUs are almost identical in performance.
I still think you just like new shiny gadgets. I don't spite you for that. It's just that the science fiction comment supports it.
I like innovative solutions. Despite the interior design that is far superior to PC counterparts, I don't consider the Mac Pro to be one of those.