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.
That product will never exist as there are only a handful of customers who would want it and even less who would pay for it.
Also, lookup the MTBF reports. It's more likely that all your Client systems will fail before a switch does.