And dams - isn't Mosul going to be destroyed soon because its dam requires constant maintenance (a clay curtain pumped into the porous bedrock) which hasn't happened since Desert Storm?
As far as Mosul I'm unsure, maybe someone else more informed can chime in on the actual state of affairs there since wikipedia/google turned up multiple contradicting results for me.
[1] https://en.wikipedia.org/wiki/Hydroelectricity#Advantages
Probably not in your lifetime let alone in a generation. Mosul's an issue because the substrate is not suitable for dam building (it's soluble gypsum, so it just keeps eroding because dam foundations kind-of tend to be around water) so the dam has to be continuously grouted to prevent it from failing.
Hoover faces no threats of similar magnitude.
It's cleaner and more reliable than any other kind of energy production on the planet including coal and oil. Nothing is 100% reliable, but hydro is the closest we're likely to get.