Not future proof for your needs, but Apple silicon Mac Pros will have an even lower future proof time, at least the first one. Those computers come with PCIe 4 not 5, and hopefully each PCI express port doesn't shares bandwidth with the rest.
Again, no. They will do what we need them to do when we buy them and will continue to run the software we need through the three years we expect to keep them. That means they are future proof.
So to your needs is half way obsolete already because doesn't have PCIe 5.
No. I made clear that we do not replace/upgrade hardware in existing machines, so we would not swap cards a year or two from now. The cards we use right now support PCIe 4. In a year or two, Apple may have a new Mac Pro, with PCIe 5 and we may be able to buy cards that take advantage of it. At that point machines we buy will use that, however, like most actual businesses, we would not try to replace cards mid cycle. You model is how hobbyists work, not how real professionals work.
I'm arguing that those intel machines have better RAM capacity.
Which matters not at all to me. They have more RAM that I do not need, nor would I buy, but lack Neural Engines and Unified Memory. Those are much more important for me than a spec that is irrelevant to me. Our 2019 Mac Pros were configured with 96GB, as that was all that our testing showed benefited our applications. That we could have spent $50,000 and bought machines with 1.5TB was irrelevant.
Obsolete for your needs, but for another person will find those second hand computers a good use.
Which matters not at all to me, as we do not sell our old machines, we scrap them. Their theoretical use by some future theoretical user that would have no impact on our use.
Not you, but some will reuse that old computer for a second life out of service.
That is not the common practice for businesses. Again, you are talking about hobbyists, who are not the target market for these machines.
So by your definition, if you need more than 192 GB RAM what does that means?
It means that I would not buy these machines. Just as if I needed to run Windows, or have 4 PCIe x16 slots I would not purchase them. However, given that the max RAM one can buy for these machines is 192GB, it seems unlikely that over their three year life span, any of the software we use would
require more than that. It is possible that some future version might be able to take advantage of more, but it would not
require it. That means that these machines as purchased would continue to meet our needs for their full three year life span.
You keep talking about situations that do not affect actual business users. No one I work with evaluates a machine by saying will this be useful to someone else for some other purpose after I am done with it. In addition, I cannot think of any software we use that has ever required the max available configuration in order to function.
Just to be clear how many 2019 Mac Pros did you purchase and how many of them were purchased with over 192GB? If you have no real world experience with this, we are we even discussing it?