The technology to convert wifi signals into the placement and identity of people is getting much better. Not by using their devices, just the waves bouncing of their bodies. (There’s nothing new to the pipeline as far as I can tell, we’re just starting to get into the accuracy ranges that make it easy/useful.)
Oh, for most usecases I can think of, there are easier ways. For example, by attacking the cellphone the person is carrying. Or watching for their gait on network cams instead of via wifi.
No phone? Hiding inside? It’s a terrrist, prol;ly