This is different though, isn’t it? Amazon still exists. The whole platform is shutting down. Individual devs aren’t taking down their apps.
The Amazon store will remain open for Fire tablets if I'm reading right, and those are AOSP-based. So it's kind of similar. Again, not that I'm fine with it, but that I think it's technically not unprecedented.
I had a Google Play app whose dev died. It was just a simple local app -- no network server usage. When I last upgraded my phone (due to imminent failure of the previous one) it refused to copy the app over -- and the app was no longer in the Play store.