> There is nothing physically limiting it from working.

Clouds, rain, atmospheric density variations, interfering signals and noise sources, phone positioning, the attenuation and reflections from nearby materials...

Also, don't forget that the SpaceX announcement was for a max of about 4 Mbps for an entire cell which they said was a very large geographic area. It will also be asynchronous short message (text) for quite a while. Next time I am backpacking in Canyonlands it will be great to have, but it will have very little impact on the vast majority of phone usage for quite some time. Its a small but important step.