Mac Pro Has SATA Ports
A bit obvious but (and I could be wrong) they never mentioned it in the keynote. This was a bit of surprise since I thought easy expandable storage would be something a lot of people would like.
Anyway [these](https://i.imgur.com/8YhdEhg.jpg) are the two SATA ports and what I assume is a custom 10 pin connected(although that seems a bit overkill for storage drives). There is also a USB port in there. I’m unsure of it’s purpose.
[This](https://i.imgur.com/nP0Opmx.jpg) is what would mount into the Mac Pro case through two screws on the top.