Just wait until these people start taking down power plants.
PING!
The attacks today were tested a few weeks (?) back - devices accessible via the internet (cameras, etc.) were hacked in masses and were used together to generate a massive denial of service attack, in the order of TERABYTES/sec on the target. The guess was this will be the new thing. In an “Internet of Things” era what you suggest will become more possible than I’d considered in the past. All devices will need to move toward authenticating connections, only working with trusted sources.
...easier said than done.