These attacks are valuable inputs for new generations, but no cause to consider 3G and 4G insecure in practice.
The authors learn about user's activity and location. But the comments often lack understanding what that means in context of mobile networks. Usually, it simply means:
* Is the user currently active in the cell?
If yes, the user's location is known (somewhere in this cell) and also his activity (he's online, otherwise he wouldn't be present). The authors here present an issue where the authentication procedure allows tracking with some probability.
It isn't like they switch off the old networks 3G, 4G etc when the next generation comes out. I also assume this cannot be fixed with a firmware update.
> In a paper proposing 6Genesis, director Matti Latva-aho explains "a new mobile generation appears every 10 years, and thus, 6G will emerge around 2030 to satisfy all the expectations not met with 5G, as well as new ones to be defined at a later stage."
