But no, that is not what I was talking about. I am saying that new explorers will likely be travelling the well travelled routes to visit the sites. While they are still exploring, they will be finding far less virgin systems.
Sure, that sounds good at first, but once again, reality intrudes. Explorers on the well-trodden routes that DW2 went through have produced several million new systems. Funny how that works.
Besides, let's say that an explorer travels 1,000 ly to reach undiscovered systems. Which is much more than they have to, but hey, maybe they are heading in a popular direction. With today's jump ranges (let's go with 50 ly), that's twenty jumps or less. Hopefully, our example explorer will then go on to explore for far more than just twenty jumps. If they explore, say, a thousand systems, then it hardly matters if they had to jump twenty or forty systems before they found any new ones. Unless they gave up fifty systems in, of course - but if for nothing else, then they'll do it for the 5,000 ly requirement for Palin (and now Chloe, who's totally not copy-pasted from the Professor) anyway.
Also that decline [in exploration] started well before the FSS came out
Except 2017. April to 2018. January saw an increasing trend. Then there was a slower but steady decrease, followed by four months of stagnation, until 2018. October. That was when the FSS was announced and later demoed, and exploration activity saw its largest drop to that date, setting all-time lows in November. (I'm saying "to that date" because the drop from that was smaller than the drop after DW2 was.) If we say that the "FSS came out", and not that it went live, then the decrease started when it did.
However, there is something else notable. This was only true for systems: when we look at bodies scanned per system, and ELWs per system, then neither ever had a downward trend, right until after DW2 reached the core. So even during the times when less systems were added, people still were slowly more and more interested in scanning the contents of said systems. Obviously, when the FSS went live, the bodies scanned per system went through the roof. On the other hand, the ELWs / systems ratio actually peaked in 2018 December, and started decreasing afterwards. That's also an interesting question: when it became much quicker to scan them, why did the ratio go down immediately?
Hm... Perhaps for new players, it's actually more difficult to recognize an ELW on the barcode than it was on the system map? After all, they are right next to the common Rocky Ice Worlds there. I did say in the past that the FSS is good for ELWs, because I meant that for body types in general - which the developers specifically highlighted - but now I wonder if it's only better for WWs and AWs instead. (Speaking of the latter, no questions there: the AW / systems ratio kept increasing until it peaked this March.)
Anyway, this is more than enough describing data. I'll publish them all once I compile a few more things that I want to check - although most of the above is readily available to everyone (without needing to work on the EDSM database dumps, that is), so if you care, you can see for yourself already. Only the parts about ELWs and AWs aren't, for those, you'd need to run your own counts.