I am building my personal private cloud. I am considering using second hand dell optiplexes as worker nodes, but they only have 1 NIC and I'd need a contraption like this for my redundant network.
Then this wish came to my mind. Theoretically, such a one box solution could be faster than gigabit too.
Why not just use a separate switch and wireless AP for redundancy? Wi-Fi can be your backup if your wired switch goes down. Assuming your Dells have Wi-Fi cards, that is.