Past experience and documents that ceased being classified shows that serious attackers (e.g. NSA) are at least decade ahead of what's publicly known in cryptography; i.e. we know that pretty much always when new relevant groundbreaking math was published, the classified cryptographers had known that for a long, long time already.
So if this attack is developed today, then you should assume that NSA has been able to execute this attack for at least ten years already whenever it suited them, including mass surveilance of random not-that-important people. The same applies for the collisions - the first published collision was 3 years ago, but we should assume that that's definitely not the first; I mean, only a minority of the world's cryptography researchers participate in the public, open, academic community; the majority of them are employed with a condition that they won't get to publish anything important. And since we know for the last ten years that such attacks were possible, there's no reasonable reason why SHA-1 would have been considered as safe.
So if this attack is developed today, then you should assume that NSA has been able to execute this attack for at least ten years already whenever it suited them, including mass surveilance of random not-that-important people. The same applies for the collisions - the first published collision was 3 years ago, but we should assume that that's definitely not the first; I mean, only a minority of the world's cryptography researchers participate in the public, open, academic community; the majority of them are employed with a condition that they won't get to publish anything important. And since we know for the last ten years that such attacks were possible, there's no reasonable reason why SHA-1 would have been considered as safe.