We have 1.4 billion devices out there running Android all running the same OS. We have roughly 1 billion iOS devices all running a different OS, but all running the same different OS. Both with significant compute power per device. We have 10 million Raspberry Pi out there. The variant 3 is quite powerful. I don't know how many routers, TV sets, fridges, running a modified general-purpose OS.
You could joke that we are just one really bad zero-day and enough criminal energy away from a Terminator 3-style scenario. The bright side: We are still protected by a lack of updates in technology from the full T3 scenario as described in "CNN: The U.S. is still using floppy disks to run its nuclear program" . By the way, this is the only case where i 'm against updates. This code and hardware did not killed us for the past decades. Keep it this way. Still bad enough: Given failing TVs, lack of Netflix and porn , no smartphone to stare at and the necessity to talk with each other ... people will go on a rampage anyway and behave like post nuclear armageddon zombies.