Yes but this didnt all go on in one city. I'm pretty sure the attacks went on nationwide. For example, if you wanted to erase Citibank's records. Just theoretically, and ignoring the backups offsite. If you just blew up the Citibanks in one city, it would do any good. Their headquarters would all have the same information in different cities, yes? So I think that the ending left open the possibility that it happened in many places, since it'd be futile just to hit all in one city.

Still, the possibility of them succeeding is still not 100%.