"How Many Species Exist? The question takes on increasing significance as plants and animals vanish before scientists can even identify them."
Now, wait a minute...if you have never identified the species, how do you conclude they are gone? Its like saying you never knew you were married but your wife left you. It makes no sense.
Nature doesn't come with a guarantee: ask the dinosaurs, Neanderthal man and the Great Auk. Nature has seen them come and go and does not care if a species finds a niche or not.