usb and ethernet connector

We usually have wifi and usb access if we buy a dongle like a 3G modem.

But I'd like to have also the possibility to plug a rj45 connector for ethernet.

So why not find a way to mix usb and rj45? 

I mean to carry two different signals through the same connector?

The solution could be to modify the usb connector in order to allow 8 channels.

Another solution could be using  a converter for multiplexing and demultiplexing from 8 eight to 4 chanels.