Re: "The absolute worst we could do is wipe out... ourselves"
I'm not a "foaming-at-the-mouth avengers-of-gaia type". I am simply aware if my insignificance in the grand scheme of time and space. You, I and, indeed, the whole Human race, exist, and will only ever exist, as an infinitely small mote with respect to the vastness of all that has been, and all there is.
The Earth has, in the past, recovered from a number of massive ecological disasters. Disasters far bigger than anything we Humans could ever inflict on it . It will certainly suffer from them in the future, whether that be from the actions of Humans (or whatever species follows us, or we evolve into), or from massive volcanism or asteroid strike (as has happened in the past).
Whatever we Humans do here and now will have little bearing on the state of the Earth's ecosystem in 4 or 5 million years time.