All of this has happened before
NPR had this report about the mass extinction of frogs in the Amazon rainforest on a few days ago. Scientists are concerned because they believe climate change has led to the over growth of a fungus which they believe is responsible for a mass extinction of frog species going on in the rainforest. My thoughts on this are, there have been mass extinctions before. The diversity of species of frogs in the rainforest arose after some past extinction event. If the diversity that we have become familiar with came about after a previous extinction event wouldn't the diversity of species establish itself again? I think the answer to that question is yes.