ethernet has as much to do with TCP/IP and DNS as does radio waves with FM radio.
ethernet is a wire protocol upon which a TCP/IP stack runs on top of. if USB looked a lot more like ethernet, it would be far easier to write drivers for devices.
USB and PCIe are not layer 2 protocols, they're vertical over layers 1-6 so I filled in the blanks of the proposal, such as it was. If you want to pick nits, do it with bsder, comparing the two is his idea.
> it would be far easier to write drivers for devices
I can only assume this comes from a place of "I know a bit about ethernet and would like to transfer that knowledge to the embedded space." It certainly doesn't come from a place of "I write drivers for the USB and PCIe stacks and think ethernet would make my job easier."
There's also the matter of what HW/FW likes, which probably has greater bearing on the situation than what SW likes, and I can assure you that they'd be even less enthusiastic about the replacement than I am. Proof: they've got a choice! If they wanted to use ethernet, they could just do it. They don't. For good reason.
(Yes, sarcasm. Two can play.)