They've been trying to kill the Mac Pro for over a decade. I wonder how long before they backtrack again? It seems like they should at least have a migration path for users who needed the expansion cards the Mac Pro supported. Pushing them to the PC seems pretty bad.
Apple's new "Pro" definition seems more like "Prosumer".
The form-factor always felt like a weird fit for Apple Silicon. With the Intel boxes it was understandable; you want a few liters of free space for a couple AMD cards or some transcode hardware. The system was designed to be expandable, and the Mac Pro was the apex of Apple's commitment to that philosophy after bungling the trashcan Mac Pro.
None of the Apple Silicon hardware can seemingly justify this form factor, though. The memory isn't serviceable, PCIe devices aren't really supported, the PSU doesn't need much space, and the cooling can be handled with mobile-tier hardware. Apple's migration path is "my way or the highway" for Mac Pro owners.
The migration path is Thunderbolt PCIe enclosures (basically eGPU enclosures but you don't have to use a GPU).