You could have skipped the dubious analysis and gotten straight to your point, you know ;)
Astral Chain did well in August. Second month sales are never big for this genre, so no surprise that it didn't hit top 20. But it's obviously not Nier Automata level of sales, of course: I believe that games did like 172k or 192k first month in the US, which is on a different level.
Nintendo has funded many projects of theirs, despite sales not being strong. That could be worth a lot I think for a contract-based studio like Platinum Games. And it remains to be seen whether they get to do Nier 3, considering Square Enix are not obligated to go with them. But regardless, Astral Chain started development well before Nier Automata launched, so doing Nier instead of Astral Chain was not even an option. We still don't know if Babylon's Fall will work out, so who knows if they are able to always repeat the success. They are talented, so I have faith, but sales have been low or development terminated for everything except Nier Automata, so the question is if they can make a big hit like Nier A without the Nier director.
We'll see, if Babylon's Fall does well, then they seem to match well with Square Enix, and should do more projects. But neither does that mean that their projects with Nintendo are not worthwhile for them (since they have creative goals that Square Enix might not all want to fulfill, while Nintendo might fund different creative projects alongside whatever SE funds).