It‘s not a very professional device if you can‘t upgrade the storage and the memory. The Mac Pro will feature modular SSDs (and they aren‘t even super fast). I wonder if Apple will use something proprietary or standard M.2 NVMe modules. They probably can‘t offer PCIe 4.0 slots since they‘re using Intel which is trailing behind.
You could make the cpu, gpu, ram and ssd user replaceable. But then you need bigger connectors, meaning you fit less stuff in.
There’s barely any unused space inside.
If you want something you can replace parts on, get a Thinkpad.
As someone who carries a MBP every day, the focus on portability is something I appreciate. So for me, I’m happy to take that trade off.