Even if it's at the top end of the predicted range, an impact would be ~40MT equivalent. Enough to level a city, but not an extinction event by any means; plus the likely impact path is across central America, the Atlantic, central Africa and north India - not really regions that have the resources to respond to a threat like this. Personally I'm hoping it misses, because I don't see the counties that could do something about it stepping up right now, so you'd be looking at maybe 100 million people displaced from their homes and an insurmountable humanitarian crisis