In ecology there is a concept called extinction vortex. It works very much like a black hole. You pass a non-return point and then the extinction process accelerates suddenly. There is just not time anymore for plans B or C. To escape the gravitational field you need to add lots of energy in the opposite direction. You need, lets say it, a "god's hand intervention"; A few humans that will decide to spend huge amounts of money, time, technology and resources to try to save the day. A struck of luck that worked for Californian Condor or European bison, but failed for Californian porpoise.

> If the metaphor you're choosing is a company losing their clients, then your argument is wrong, because what happens is that the competitor(s) fills the void and the system balances itself.

What you say is exactly what I'm predicting that will happen.

If you wipe an obscure species of mosquitoes, and they pollinate X, in the 99% of the cases X will disappear. Period. There is not time for the other species to fill the gap or for X to adapt. Can survive only by cloning itself. If all mosquitoes were equally equivalent and equally replaceable, we would have room in the planet for one single species, not thousands.