I don't work with this myself, but my understanding is that you only start ripping this out when you are positive every wavelength from every customer actually has coherent detection, and that could take a while. :-) Obviously this will differ from site to site, too; I would assume new ones don't care unless there's a lot of legacy involved.

And the time for the lambo and the tractor will depend on the round trips each will have to do, so it depends on the medium.

Almost all of them deploy their strategies within exchange colo's already

They’ve been using hollow core fiber (and funding research into it) for nearly a decade. I know it goes back further than the 2017 spinoff mentioned in the article, but https://optics.org/news/11/9/52 talks about it a bit.

I've often wondered if for HFT or similar it might be worth pointing a particle accelerator at the floor and going for direct-line transit times. I'm fairly sure that this is theoretically possible, but no idea if the engineering challenge is beyond reach for use as a communication link.

then you have online video games. increasing the area where you can get good connections increase quadratically (or more, if we hit step function = big city get in range) the viability of niche multiplayer video games and it is thus a boost to creativity.

there are probably many more niches... (need to think of reachable area, quadratic, instead of 1-to-1 link linear)

A hammer is not more obsolete for driving a nail because pneumatic nail guns exist.

Using just a hammer on a commercial framing job is silly, however, because pneumatic nail guns work better. Everyone still has a hammer ready though, because it is still needed.

Using a pneumatic nail gun to hang a picture is silly, because it is so overkill (and expensive) that it actively makes it harder to do the job.

This tech doesn’t obsolete existing fiber for last mile because the extra cost associated with producing and splicing it dwarfs any potential gains (which would likely be in the 10’s of ns).

If it is proven to work well, this may obsolete existing transoceanic/transcontinental fiber runs, where the latency difference will be noticeable enough the cost is worth it. However, it’s highly unlikely that anyone will actually turn down any of these existing lines. The different is not so much that the old lines are useless.

If, eventually, this new fiber is at the same price point and as easy to work with as the current fiber? then the current fiber will be obsolete.