Or it could happen by some freak accident 5 minutes from now.
Your response was aimed at strengthening the computationally expensive argument.
Why are we using a 160 bit hash instead of something that is more resistant to collisions? Will we be able to move to a 224/256 bit hash if and when the need arises, even if it's 100 years from now?
You could use 4096 bit hashes, and still get a freak accident in 5 minutes.