Is critical infrastructure the next DDoS target?

The massive Distributed Denial of Service (DDoS) attack last month on Dyn, the New Hampshire-based Domain Name System (DNS) provider, was mostly an inconvenience.
While it took down a portion of the internet for several hours, disrupted dozens of major websites and made national news, nobody died. Nobody even got hurt, other than financially.
But the attack, enabled by a botnet of millions of Internet of Things (IoT) devices, inevitably led to speculation on what damage a DDoS of that scale or