As for GPUs, I've read somewhere that Apple devs had told that two pie lanes had 8-pins connectors, which basically means that you can put standard GPUs inside the new mac pro without using the new special module. As for nVIDIA, it will only be a driver problem, and this is not likely to change in the near future. Another question is the ability to change the storage without being blocked by the T2 chip. Unfortunately it was a news on my phone feed, and I can't find it back.
Anybody Know how much is the Bare Case on Wheels I like that bit?