I can tell you as someone who read the papers on very early deepfakes and AI video generation with amazement followed by dread, this is going to be feasible on a large scale in a short period of time. Researchers do stuff on an absolute shoestring budget usually, it's incomparable to what large companies and governments have at their disposal. There are already consumer products that were able to become fairly precise motion sensors with just a firmware update. Next gen devices will be built with motion fingerprinting in mind, I can almost guarantee it.

It gets more accurate with more access points, too. So corporate and education settings will be the easy places for this to get implemented.

It's also only possible because the information they used (BFI) is unencrypted.

It's a start. It may take time to make it work for "everyday" use, but if it's possible now, it can be done better in the future.