First- you are going to have to move past the fatal logical assumption cetaris paribus...all things are not equal.

The cost of flooring communications satellites are changing dramatically. And there other options than geosynchronous orbits with NASA or Ariana vehicles.

HALO (high altitude, low orbit) platforms are one. And they are not even 10 miles above the surface. Some are ballon platforms that are periodically rotated to create a terrestrially percieved persistent platform. (And there are routers in those already!) Some REA applications have been made for cellphone and rural telephone IP service platforms.

Even for the TCP session limits that you point out- many of these systems don't have to be symmetric, short bursty messages. Fleetsatcom is an example of the early architectures used asymmetric streaming with common, broadcast or multicast responses. So the legacy deep space (military definition of the region of space) satellites have plays with other than the commonly depoloyed terrestrial layout with point to point communications and serial, terestrial link response times.

The emerging world wants and needs a different equation than the ones being outlined here. The old model serves only the incumbent nations and suppliers. And we are already moving away from the 500,000+ hour MTBF models of yesterday.