Think carefully about paying the extra for cellular. The cell radio failed on my iPad, and I learned I really did not need cellular. Today WiFi is available at many locations, and when it is not an iPhone works well as a hotspot.
This is the first time I've heard about failed cellular chip... as for hotspot, it's fine if you use it few times a year, but when traveling abroad or on-the-go, where I prefer not to use public WiFi, it's inconvenient and it kills the phone’s battery.