How much space in the chassis will satellite connectivity take up? If it was a zero-cost feature both in terms of not adding anything to the end-user price of the phone and also in terms of not taking up any extras space in the chassis because somehow the functionality could be added to existing chips without increasing package size and an existing antenna could handle the satellite comms as well as what it was already doing then great and I would be all for it but, given that I would be very surprised if that later point was the case (and knowing Apple I’m sceptical that the first point would be the case either), this makes me very nervous. I’m worried that the extra internal space needed for the satellite hardware will be at the expense of battery space because Apple doesn’t want to increase the overall size of the phone (understandably for the Pro Max) so, after a great run of Apple actually increasing battery life year on year we might go back to the bad old days when in some years battery life on a new model was actually worse than that of the year before because battery capacity gets smaller and year-on-year improvements in electronics efficiencies don’t quite make up for the smaller batteries.
I suspect it will take up zero space because it won’t be there. I’d take the the rumors more seriously if they discussed the service model. I have an inreach and pay $30 a month for periodic tracking and a limited number of text messages. The satellites don’t have capacity for 100s of millions of people sending “emergency” texts every time they are out of cell service. If there is an emergency, who is contacting the local authorities about the emergency? You need to have or partner with an emergency dispatch center with 24/7 staff.
With respect to your concerns about battery life, it is even more important for an emergency device to have a long lasting battery. My fear is that if they do implement it, it will be a poor one and offer a false sense of security. While taking people off paid services that do work.