While Starlink will be available everywhere in the world eventually, it will never be available to most consumers in the world. That is because it can only handle a small group of subscribers in any area so it can only serve everyone in rural areas, not in the urbanized areas and urban clusters where 80% of Americans live. Here is how Elon Musk explained it at the Satellite 2020 Conference:
The challenge for anything that is space-based is that the size of the cell is gigantic . . . it's not good for high-density situations. We'll have some small number of customers in LA. But we can't do a lot of customers in LA because the bandwidth per cell is simply not high enough.
Where Starlink will compete in urban areas is in providing mobile network operators (MNO) with backhaul services, connecting cell towers to the internet backbone. With 5G not only will mobile data grow but the MNOs will be competing with cable in providing residential service. In originally announcing Starlink, SpaceX said that it would have the capacity to handle 50% of the increased worldwide backhaul volume.