There have been no signs of the Borg since Voyager’s return in 2378. That’s seven years.

Do you actually believe that seven years, or twenty years, or a hundred years, would be anything more than a brief setback for the Borg? The Borg do not consider time as shallowly as humans do. The Borg are not limited by the life spans of individuals. The collective lives on. What one knew, all know. What one remembers, all remember.

Isn't it possible that Admiral Janeway's actions destroyed the Borg?

That would be a lovely fairytale. Admiral Janeway's actions likely destroyed that hub. But the Borg are far wider spread and have contingency plans dating back to before humanity achieved warp speed. We may have delivered a crippling blow, but it was not a killing blow. The Borg still exist. So long as they exist, they will not accept defeat. They persist. They choose a goal and continue until they achieve it. The Borg are infinitely patient. They can afford to be.

I understand that Starfleet may wish they were gone. I do not understand the stubborn refusal to deal with reality. We cannot simply ignore the Borg threat and assume they will not notice us.

The dissolution of the task force was unfortunate and ill conceived. Wishing that the Borg won’t return does not make it so.