In my case, the USB-hub, speakers, webcam, and microphone still work. Only the display's stopped working. As I mentioned in my original post, the Studio Display continues to work as expected with my Mac.
I've attached the output of `dmesg` when I connect the Studio Display to my laptop via USB-C. My laptop detects two devices -- the USB2 Hub and the Studio Display -- but it does not recognise a display.
[99149.206027] usb 1-2: new high-speed USB device number 14 using xhci_hcd
[99149.335440] usb 1-2: New USB device found, idVendor=05ac, idProduct=101d, bcdDevice=52.12
[99149.335446] usb 1-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[99149.335448] usb 1-2: Product: USB2 Hub
[99149.335450] usb 1-2: Manufacturer: Apple
[99149.335451] usb 1-2: SerialNumber: [...]
[99149.336673] hub 1-2:1.0: USB hub found
[99149.336996] hub 1-2:1.0: 4 ports detected
[99149.656027] usb 1-2.4: new high-speed USB device number 15 using xhci_hcd
[99149.761681] usb 1-2.4: New USB device found, idVendor=05ac, idProduct=1114, bcdDevice= 2.01
[99149.761688] usb 1-2.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[99149.761690] usb 1-2.4: Product: Studio Display
[99149.761692] usb 1-2.4: Manufacturer: Apple Inc.
[99149.761693] usb 1-2.4: SerialNumber: [...]
[99149.766410] usb 1-2.4: Found UVC 1.50 device Studio Display (05ac:1114)
[99149.937902] hid-generic 0003:05AC:1114.0020: hiddev96,hidraw2: USB HID v1.01 Device [Apple Inc. Studio Display] on usb-0000:00:14.0-2.4/input5
[99149.944836] hid-generic 0003:05AC:1114.0021: hiddev97,hidraw3: USB HID v1.01 Device [Apple Inc. Studio Display] on usb-0000:00:14.0-2.4/input6
[99149.946405] hid-generic 0003:05AC:1114.0022: hiddev98,hidraw4: USB HID v1.01 Device [Apple Inc. Studio Display] on usb-0000:00:14.0-2.4/input7
[99149.948394] hid-generic 0003:05AC:1114.0023: hiddev99,hidraw5: USB HID v1.01 Device [Apple Inc. Studio Display] on usb-0000:00:14.0-2.4/input8
[99149.951171] hid-generic 0003:05AC:1114.0024: hiddev100,hidraw6: USB HID v1.01 Device [Apple Inc. Studio Display] on usb-0000:00:14.0-2.4/input9
It's interesting to see that several other people have had a similar experience. I suspect this was an unintended consequence of the 16.4 update. I hope that Apple redresses this issue in the future. In the meantime, I'll be using my laptop's tiny built-in display for work...