I own a Garmin InReach that I regularly take with me on hiking expeditions (mostly Scotland, Iceland and South Africa) and it’s super handy on remote areas with no coverage. The ability to send an SOS is the main feature, but the two-way messaging system is just amazing for peace of mind, for me and my family.
However, the main thing about the InReach is its ruggedness and battery life, which I consider essential. I always carry an iPhone with me that I use when and if I get reception, but I need to carry a battery pack for it and it’s always in the back of my mind that an iPhone is a relatively fragile device and it’s one misstep away from cracking/breaking/etc, hence the inReach.
Moving forward, having both will be great, but I think having to rely only on an iPhone would make me a bit nervous, so I’m not sure how much of a threat this is for the inReach devices (at least for now).