I keep waiting for RJ-45 to fail to keep the pace with the gigabits, for many years. And it always catches up. But maybe not anymore. Here's what the connector looks for QSFP-DD, a standard module connector for 400GbE:
Two rows, baby, same as on USB3.
These speeds are mostly used between leaf and spine switches, but I'm sure we'll see them in the upstream routers, too.