I wasn't sure how to suggest a correction for the timeline, so here goes. This prediction is factually incorrect: http://futuretimelin...#earth-asteroid
Impacts of this size tend to happen every 100 million years or so.* The last such event occurred 65m years ago – resulting in the extinction of the dinosaurs.
If humanity or its descendants are no longer around to protect it, any remaining life on the planet may be in danger of a similar mass extinction during this time.
The mistake stems from a misunderstanding about the probability of such an impact. while there does tend to be very roughly 1 such impact every 100 Myr, the chance of one happening does not increase the further we are from the last impact. On the contrary, every day (including today) the probability is the same. Even if there was an impact yesterday, the chances of one happening today would be unchanged. Hope this helps.