It seems plausible that it would help with latency, but not by a game changing amount. This is 70/550 or 13% closer. Not all of the latency is caused by distance to the the satellites (e.g., terrestrial latency is not 0), so my guess would be that the latency experienced by users would improve by less than 13%.

Should be about half a millisecond round trip difference. 70 km / speed of light = 233.5 microseconds one way duration.