I know the idea is shocking, but they could have made the darn thing just a tiny bit larger to solve most inherent issues (including room for a PCI graphics card even)...(heresy I know). It IS supposed to be a "desktop" after all.
The real question is whether this new Mac Pro coming out will have ANY internal expansion or if it will be some crazy Apple proprietary case stacker or something equally weird. Why Apple wants to reinvent the wheel just for looks instead of function is beyond me. I just want a functional reasonably upper end desktop without compromises that doesn't cost the price of small new car.
IMO the solution to the issue is not to change the Mini but to provide another offering for those where the Mini falls short. A medium sized tower (or desktop) system which permits upgrades / expansion.
I've been reading a lot about the new Mini and I've noticed a pattern: People asking what CPU and SSD to purchase. One thing most are not inquiring about is how much memory they should get. Why is that? Because it can be upgraded. People are faced with this dilemma because they have to get it right the first time.
A member started a thread about being undecided about getting the 256GB or 512GB SSD. Despite the much vaunted high speed I/O ports available on the Mini the consensus appeared to be the member should go with the 512GB drive.
Then there's the thread about SSD performance where, as is expected, the smaller capacity drives have lower performance. Not only is one stuck with the capacity they purchase the Mini with but they're also stuck with the performance.
I recently purchased an HP Z440 system. It has a quad core CPU, 16GB RAM, low end video card, 1TB SATA HD (non-SSD). As I wanted to install an SSD I purchased a 1TB Z-Turbo drive (NVMe SSD) and plugged it into one of the PCIe connectors. I also needed a media card reader which was easily installed.
Given the system is upgradeable I didn't have to go seeking one which already had the 1TB Z-Turbo drive and a media card reader. I merely had to buy what I needed and install it (Z-Turbo drive took all of 60 seconds, the media card reader a couple of minutes). If I want a faster CPU I can buy one and easily install it. If I need more memory I can easily install it (up to 256GB). If I want faster video I can easily install it. If I want Thunderbolt I can easily install it. It's a medium sized system that fits neatly on the floor right next to my desk. It's out of the way and the location makes it easy to turn on, insert USB drives and the various media cards (CF card for my digital cameras).
This is post is not intended to be a PC versus Mac post but rather to show the benefits a medium sized tower (or desktop) system can offer. For those who want compact size the Mini should be their choice. For those who need more or don't want to be locked into the initial configuration a medium sized tower / desktop offering would be their go to system.
I know Apple isn't going to go down this path but I find it interesting so many people are willing to adapt to Apple instead of expecting Apple to adapt to them.