Apple confirms the Mac Pro is over

[Citysnaps]

All that can be done with Raspberry Pi or Arduino type boards and USB-C-connected back into PCs and Macs. The biggest demand for I/O bandwidth are desktop graphics cards and Thunderbolt 5 can give high performance even there, though short of maximum.

Everything on your list can communicate via USB 4, most with USB 3.2.

Sure, *maybe* it can... But that's a large collection of boards that would be difficult to sell to customers (mostly defense/aerospace/government) that want a turn-key rack mount chassis (along with analysis software), ie a product, that can be deployed with their current signal analysis systems. In other words, they want a rack mount box that's ready to go, and helps solve their analysis problems.