Limited by the amount of satellite coverage? Or on the ground limitations from ever greater division of bandwidth? I guess those two are directly correlated, but they could in theory add microwave relays into the mix to help offset higher population dense areas from lower density ones with less used bandwidth.
I think it's mainly a limitation of the beam steering: terminals that are close together need to be seperated in bandwidth so that they don't intefere with each other, and there's only so much bandwidth available. Tighter beam steering could help but that is something that tends to bump up against physical limitations.
(and it's an area where it would need orders of magnitude improvements to address the density of cities, it's not really close at the moment)
In the past I've worked on consensus based protocols like the ones used in modern cellular systems; basically edge devices register with a controller system that then coordinates time slots for distribution/use of bandwidth for the limited spectrum. Adds a lot of complexity and requires highly accurate time synchronization mechanisms to have any hope of working, but they certainly could leverage something like that to further increase support at higher densities. That is, if they're not doing that already.
