You don't know if the virus was doomed to failure or not. You also don't know if the Borg already considered the Federation a viable threat or not. As I have told you before Anwar, THE BORG WILL NOT SEND ANY MORE CUBES THAN THEY NEED TO, OTHERWISE THEY WOULD HAVE SENT MORE THAN ONE CUBE IN STAR TREK: FIRST CONTACT. Also, you keep repeating yourself, WE ALREADY KNOW WHAT YOU THINK ABOUT THE MATTER, IF YOU HAVE NOTHING NEW TO ADD, STAY SILENT!
Why are you yelling and being rude? At least be right if you are going to do this. Your argument is completely illogical and is refuted by later canon. It is not logical to say "The borg don't send more vessels than they need to or else they would have." Clearly, we the viewers do not have the extra information of knowing what exactly the Borg's motives are with the Federation at every single juncture, but I think it is safe to say that if they wanted to truly trash the Federation, they could have.
It is made clear on at least two separate occurrences that the Borg clearly DO send more vessels then necessary when they want to. This happened in Hope and Fear as well as Dark Frontier. In Hope and Fear, "hundreds of cubes" were sent to assimilate 1 planet. In Dark Frontier, at least 4 Borg vessels including a Cube were sent to attack a planet of just over 100,000 lifeforms. Imagine what they could and would send to the Federation. This is more recent canon in our timeline as well as the Star Trek timeline, so I suggest you read/watch up on Borg history before making dramatic and incorrect proclamations about the Borg and then telling people to shut up.