They'll just move on to something else to try and scare us all to death.
I figure it will be something to do with "Clean Water".
Some of the “Chicken Little” scenarios from the last century:
1. The Coming Ice Age
2. The hole in the Ozone Layer
3. Nothing will ever grow again in that place(Hiroshima, Bikini, Three Mile Island, Chernobyl)
4. Acid Rain
5. Ozone
6. El Nino
7. La Nina
8. Overpopulation
9. Globull warming
Now the threats of these have been abandoned in favor of convincing people that we are all descended from Ancient Aliens who mated with Freemasons,while burying gold in remote locations of north America using Interstellar technology and Druidic Spells while contemplating a marriage between Jesus and Mary Magdeline resulting in offspring who became Templars.