Starlink could do significantly better in theory once the constellation of satellites with laser links is operational. The speed of light in vacuum is much higher than in optical fiber. If the data can be routed in space and travel directly from source to destination terminal instead of bouncing to and from ground stations then under 100 ms should be achievable. The light speed limit would be 50 ms (assuming that the data can't cut through the Earth's core).

It's unknown if Starlink will routinely route packets directly between user terminals or if that will be a special service sold only to customers willing to pay a premium. We'll see when the constellation is ready.

The increase in travel time comes from: extra path length from bouncing between the sides of the inner fibre (depends, maybe 20%?) and from refractive index slowdown (about 70%). But then you have to worry about the greater total path from going into space, and also mux/demux/boosting delays.