They could put-compete if they can create an iPhone with extra powerful antennas or other hardware. Like they always do- own the full stack to allow it to work better.
Especially for fashion statements like iphones. (Doubt this? Upthread people are discussing how certain affluent neighbourhoods only have iphones).
You could potentially control the situation enough where a user can enable “satellite mode” which uses extra power for sending messages. It’d affect battery life, and need to be manually enabled, but it’d enable better connections in emergencies.
You could try to improve directional antennas and some sort of aiming system with the screen.
Lots of things that maybe could happen when you control the client side instead of just the satellite side.