I would also assume not. It says on Microsoft's site that when you connect an external drive to the Xbox One, it "prepares it for use," or something. I assume that means it'll format it, and it does it in its entirety. I don't know that you can create a pair of partitions, on e the Xbox One can't see or touch, to get it to serve as a dual-purpose drive. On top of that, connecting it via USB and Ethernet at the same time? I imagine that SOMETHING would get mad.
What intrigues me is whether or not the Xbox One could read a properly formatted NAS drive, like a MyCloud or something. I doubt it, but it would be cool if the Xbox One could grab that stuff. You could then have multiple Xbox One consoles in the house, connect them to the formatted drive wirelessly, and have them share it. That's what they should work on.