Re: Does it matter ?
I don't think that is the case. IMSI catchers are quite effective and not hard to get and deploy, today. If this attack can be made easy to use and automated into a "next-gen IMSI catcher" then that is a serious issue for 5G security as many more journalists and "bad guys" will be able to use it than have access to the lawfaul-intercept route.
What is not clear from the article is whether this attack only provides metadata such as MSISDN or IMSI or whether it can be turned into an attack on the encrypted content (data or voice).
Of course, there is plenty of time to solve it. Anyone capable of using this attack will have already worked out how to make the target's phone fall back to (insecure) pre-VoLTE technology (such as 3G) today . It will be some time before phones stop doing that.