Tue Dec 19, 2017 12:59 am
All Pi SoCs to date have a single, external, interface. That is one--count it, one--USB 2 port. The maximum data rate for USB 2 is 480Mb/s, so even without the various protocol overheads involved, you're never going to run a single connection at better that something less than half the 1Gb/s rate.
In order to get what you want, several things would be needed, any of which would require a new SoC, so the up front development cost is going to be in the multiple millions of dollars out of *somebody's* pocket,
Besides the question where you would put a second Ethernet jack, it would take either an SoC with USB 3 (10Gb/s) or one or more native GbE interfaces. I can see general utility to USB 3 and--in some limited areas--utility to GbE, but having 2 GbE ports would be specifically supporting a very small set of uses. It would be far better to stick with the current 4 USB ports and a single Ethernet port, even if those were USB 3 and GbE and then let those that need a second GbE buy their own USB 3 to GbE adapter.