> I think a dual modem would be really cool, maybe with some features targeting users in poor cell coverage/ spotty service areas.

Can already do iMessage over satellite. Most “data” is download and I predict some satellite service that sends basic broadcasts (traffic, news, Text-to-speech podcasts) squeezed into a few mbps by pointing your phone at the sky (or a small cabled antenna for around the clock use). Would love to go carrier-less.