[flacebo]

I think you highly underestimate the compatibility problems it would cause.

You'd have to replace the global networking infrastructure. Starting from every wall plug to the switches and backbone devices. The new connector would have to be easily crimpable, and hopefully as cheap as RJ45, I don't think you could go much slimmer.

All of this just so your end device can be a little bit slimmer. Definitely not worth it.

Using both at the same time so you could leave the backbone alone might work, but this already exists in the form of a usb type-c network adapter.