I actually would like to address this. I like to think of the Queen as a mix of biology, technology, and digital ascension. From the Borg Collective's point of view: the Queen's cube is destroyed near Earth, her sphere goes back in time, and then nothing changed. She would still exist within the collective digitally. In VOY "Dark Frontier," she rebuilds her body to interact with Seven. Her ship is destroyed at the end of the tele-movie. In "Unimatrix Zero," she's rebuilt once more, wanting to get personal with what's going on. At the end of part 2, she's physically alive and well. This explains why in "Endgame," she lowers out of the ceiling whole, no need to rebuild this time. By tele-movie's end, she's killed - again, for good this time? We don't know. Picard's final episodes made it clear she digitally survived and was rebuilt yet again. This time, there's reason to believe she's gone for good. Well, except she still lives as an alternate-tiimeline counterpart who was the same person for centuries or millennia up until running into the Confederation in the mid to late 24th century.
What do you think of this?