My biggest fear regarding dying from an asteroid strike is not about the asteroid hitting me or the city I am in, but from unintended, extemporaneous consequences like someone in Russia or China panicking and launching a nuke at it, missing, and hitting France or the US or some other nuclear-capable nation and starting WWIII. Or an asteroid hit in Pakistan or India being intentionally/accidentally mistaken as a nuclear strike by its neighbor, and starting WWIII. Or an asteroid hitting a defunct Russian spy satellite, which was really a nuclear launch platform, and setting off the bombs, and starting WWIII. Or any asteroid strike anywhere being used as a convenient excuse by anyone to start WWIII.
So, in summary, the most worrisome unintended consequence of an asteroid strike is WWIII. Let's see the TFA's author gin-up some odds on that one.