a display at 3840x2160@60hz will eat up about 19.8gbps. Two of them together will use 39.6gpbs.
Thunderbolt 3 only supports 40gbps. So if you have peripherals that need anything more than basic mouse/keyboard (in my case, a decent webcam and a usb to ethernet adapter) this setup will fail.
According to this [1], that signal would require 12.54Gbps, so with a link budget of 34.56Gbps - 2*12.65Gbps, you'd have about 9.48Gbps left over for USB and ethernet (which is on the PCI bus for this particular hub). I suppose these numbers include coding overhead for the physical link, but I can't say for sure. If you wanted more than 60Hz or more than 24bit/pixel, you'd definitely run out of bandwidth with two monitors and USB/ethernet.
[0] https://en.wikipedia.org/wiki/HDMI#Version_2.0 [1] https://linustechtips.com/topic/729232-guide-to-display-cabl...