At the risk of seeming dismissive, the value of satellite direct-to-device service is a “nice to have, once in a while” for many of us. The exception will always be emergencies or disasters, when D2D value is very high.
I think most of us would probably rank text messaging and mobile broadband as more-important features, though, most of the time. And yes, some might still say it was the liberation of voice communications from "place-based" to "mobile" which should still be on the list.
But even if emergency messaging and basic satellite fallback is the initial attraction, followed in some cases by more support for broadband access on the mobile device, some might say a possible shift is some impact on household rural internet access, for some users.
Obviously, a stationary user can use a standard dish to get access at higher speeds. But there will be some use cases where even lower speeds are useful because one requires mobility.
Not to downplay the value, but satellite direct-to-device connectivity, most of the time, might not be viewed by most users, as among the most-important mobile technology innovations.
And forecasts of global usage still vary by an order of magnitude. The number of users still will likely eclipse stationary satellite internet usage, though.
Three different layers of impact are possible:
home broadband replacement in rural areas
backup/backup-like connectivity for households and travelers
mass-market phone connectivity for emergencies or light data use.
As a consumer user who spends most of his time in urban areas, I only encounter mobile service dead spots occasionally, with one exception: mountainous rural areas. The annoyance tends to be sporadic and limited, so most of the time, service loss might not be mission critical.
Rural residents will see the value more directly. So will some business users, especially where dedicated gear can be replaced by standard smartphones.
Other settings, such as at sea or if there is a disaster or other emergency, also have value. I’m not a fan of people talking on their phones on airplanes so I’ll consider that a scenario where loss of voice is not an issue.
Then there are the vertical applications (transportation, sensors).