I'm really curious why you care about the ecosystem if humans went extinct. It feel extremely unnatural to me, to put another species over their own.
I mean oxygen producing single called organisms drastically altered the environment. They were not conscious to actually notice, but we are. But tons of species went extinct and the earth was irrevocably changed due to their presence.
Thinking humans are special on the cosmic timescale is just arrogance.
Agreed - I don't find anything to disagree with in what you're saying.