Not just TDMA - lasers in vacuum travel at the speed of light, but signals in optical fiber and coax copper are both 2/3 of that. This means that if (and that's still an if, not yet a when) starlink does laser between satellites it can beat terrestrial speeds.

I could see the end result being that we still do bent-pipe signaling over land and only laser interlinks for crossing oceans and for customers that pay for low ping to financial markets.