I think it will be a while before Hornby can sell anything like this train set.
We’ve been able to produce quantum levitation for a few years now and those of us outside the field get to catch up with progress now and then through demos. This demo is a great one. A Japanese scientist takes the time to use a mock-up train set.
The liquid nitrogen is being splashed onto the train because the “floating” object must be very cold. Just watch how swiftly it travels around the fairly complex track. Even the tight loop isn’t enough to throw it off course.
You can watch a little more about the technique with this video on Quantum Locking the magnetic field in three dimensions. Trains not your thing? There’s also this video that tries to use the technique to re-create Wipeout.