There will always be MITM attacks for radio networks, whether at initialization, a de-auth, jamming, etc. Cell site simulators (CSS) are still threats.

While the original 3G-based IMSI attacks are not as useful (because few devices, if at all, use 3G anymore), the approach is still a known tactic for street-level surveillance.

Groups like the EFF wouldn’t put out projects like Rayhunter if these kinds attacks weren’t considered relevant. And, especially now, they are relevant.