Yes but many....nay .... most ....the max distance will be from their own back. Sure it can do 5 tx's but most wont spend 2 grand for the max capability for family monitoring. Now that's not to say I wouldn't buy a few..
Yes other functionality is where they need to up their game if they want wide adoption.
Garmins underwater vital signs are cool but lacking. Personally I would like to see location over text/ vital signs being introduced.
When Liquivision was using this tech, I thought they had developed text messaging and directionality to another transmitter. Thus, a diver could "text" for help or assistance, and the other diver would have an approximate heading if the distressed diver was out of view. That would be a good next step.
Also, develop a sonar-based HRM strap so that for swimming or pool workouts you could get "real time" HR information (don't really need that for dives, but could be nice there too for some folks).
For remote live-aboard divers, boat divers, and drift divers, the satellite linkage to the inReach system is a real game changer for safety in the event a diver gets left behind.
Lots of potential in the system, and truly top of the line even now. I have one on order from my LDS.