I can see the VR fad returning thanks to the 20-year nostalgia cycle! More seriously, I do think the standard arguments against 3D UI will carry less force in

I can see the VR fad returning thanks to the 20-year nostalgia cycle! More seriously, I do think the standard arguments against 3D UI will carry less force in the not too distant future (i.e. over the next 10 to 15 years), because of new(ish) I/O capabilities which will allow people to make more use of real-world spatial abilities to interact with computers (e.g. motion/vision control), and allow more ways to use computers to manipulate the physical world (robotics, 3D printing, ...)