These first satellites don't have the free-space lasers I modelled in that paper, but my simulations show they can still beat fibre on many paths without inter-satellite links, by relaying via groundstations:
Later satellites will have inter-satellite links, but probably not till near the end of this year, and most of the first phase will already be deployed by then.
Indeed, and I mention microwave links in the paper linked above. But those are relatively short distance: New York - Chicago, London-Frankfurt, and similar. Where Starlink and Kuiper can provide real latency benefits is on long distance paths, trans-oceanic, or passing over countries where it's geographically or politically infeasible to built microwave links.
