Vendor lineage
SpaceX - low orbit, and what it does to the latency floor
The constraint that could not be engineered away was engineered around, by moving the satellites.
SpaceX operates a low-Earth-orbit satellite constellation, and its relevance to this timeline is a single number. Where geostationary orbit sits around 36,000 kilometres up, low orbit is a few hundred - which collapses the round-trip latency from roughly half a second to a range that ordinary protocols and interactive applications can work with.
The trade is not free and it is the reason nobody did this earlier. A satellite at that altitude is only overhead for minutes, so continuous coverage needs thousands of them, constant handover between them, and a launch economics that makes replacing the constellation routine rather than catastrophic.
Read beside the Hughes entry it makes a general point about limits: the geostationary latency floor was never a technology problem to be solved by better modems. It was a consequence of a choice of orbit, and it moved only when the choice did.