You'll be happy to know that the current latencies are about two orders of magnitude higher than what going at the speed of light will offer.
That makes me think that we will easily see a 10x improvement in latency in 15-20 years.
I am suggesting this will be significantly more optimized, not how fast you can communicate over long distances.
Even with free space speeds and tunnels through the earth you only get like one order of magnitude.
I don’t know if these numbers are true, but poster was not claiming faster than light.
1) speed of light in fibre is 2/3c - unlikely to change soon 2) fibre is laid in the ground on a circuitous route - rarely changes but does happen 3) queueing delay - that's often the main culprit, changeable, but hard (see the buffer bloat debate)