How the Borg Queen Survived

Bear with me, this may get a little weird.

When Picard inquired how the Borg Queen survived the Borg Cube exploding in TNG: "Best of Both Worlds" (BoBW) she replied "You think in such three-dimensional terms, how small you've become." Now, since the fourth-dimension is time this implies that time travel was somehow involved in her escape from the Cube.

So, using that as a basis, here's my theory on how she survived:

Sequence of events

1) Riker's deflector weapon fails due to the Collective knowing of the plan from Locutus. Borg Cube heads off towards Earth while Enterprise undergoes repairs.

2) Using information stolen from the Enteprise-D's databanks and Picard's knowledge of Wesley Crusher's nanites from the TNG: "Emergence" incident earlier that year, the Borg develope new nanoprobes which assimilate species faster and allow a greater rate of production for external Borg hardware on their exo-skeletons. Picard briefly acts as the test subject for these new nanoprobes, and takes on the appearance of the "First Contact" Borg (seen in the sequence at the beginning of "First Contact"). Since he is meant to be a voice to convince humanity to join the Collective however, it is decided to return him to standard Borg form since it allows him to appear more Human. Some Borg in Locutus' Sub-Matrix are also upgraded and put aboard the Borg Queen's Sphere inside the Cube.

3) A Federation "fleet of over 40 starships" amasses in the Wolf 359 system under the command of Admiral JP Hanson, awaiting the Borg Cube which must pass near the system to get to Earth. Klingon starships are en route but may not make it in time.

4) The first skirmishes with the Borg Cube. Instead of destroying the Starfleet vessels outright, the Cube slowly disables the ships and boards them, assimilating crew as they go along. Riley Frazier of the USS Roosevelt (VOY: "Unity"), the Human woman Laura of an unknown vessel (VOY: "Unimatrix Zero"), and Marika Willkarah of the USS Excalibur (VOY: "Survival Instinct"), are assimilated and brought to the Borg Queen's Sphere on the Cube.

5) The Borg's tactic of assimilating crews instead of just destroying the ships proves to be an error as it buys time for a fleet of Klingons starships under the command of General Korok (VOY: "Unimatrix Zero") to arrive and engage the Cube alongside the few surviving operational Starfleet vessels. Korok's ship is captured despite attempts to self-destruct and its crew (including the General) are assimilated and brought to the Queen's Sphere.

6) The attack by the Klingon ships, whom the Borg have not encountered before and have not yet adapted to their weapons and tactics, proves to be a fatal weakness for the Cube. Her shields failing, the Borg Queen decides to launch her Sphere and escape just before a Klingon ship, exploiting the weakened shields, rams the Cube and destroys it. Under pursuit by the Klingons the Sphere opens a temporal vortex and goes back in time, carrying all of the assimilated Humans and Klingons from that timeline with it.

7) The Queen's Sphere emerges from the temporal vortex in the path of the same Borg Cube it just left before it goes into combat against the Starfleet vessels. The Queen warns her counterpart from the past not to waste time assimilating the Starfleet vessels, but to just destroy them outright. She then proceeds with her newly assimilated drones and the "First Contact" nanoprobe upgrades back to the Delta Quadrant. The new nanoprobes begin being added to the entire Collective over the next couple years with a few interruptions from the Hugh incident which slowed things down.

The normal flow of events from "Best of Both World's" resumes:

8) The Borg Cube engages the fleet at Wolf 359 and wipes out 39 vessels. Only the USS Endeavour under Captain Amasov is able to escape intact, though the Ambassador Class USS Excalibur has some survivors and is able to be towed back to port, refit, and returned to duty in time for the Klingon Civil War and blockade of the Romulan resupply fleet (it's surviving crew are reassigned before this mission). Riley Frazier of he USS Excalibur is killed, along with the Human Laura aboard her ship and Marika Willkarah aboard the Roosevelt. The Klingons never have time to arrive and render assistance.

9) The Cube moves on to Earth and Locutus / Picard is rescued from the Collective by the USS Enterprise and is used as a Trojan Horse to program a "sleep" command into the Borg Cube. This causes a feedback loop and the Cube self-destructs. The Borg Queen from this timeline perishes in the attack whilst her counterpart from the previous timeline escaped back to the Delta Quadrant.

10) USS Voyager and USS Enteprise-E later encounter Humans and other Alpha Quadrant aliens from Starfleet (and their civilian families who were unable to be evacuated in time) who were presumed dead at Wolf 359 along with assimilated Klingons even though no recorded encounter between the Klingons and the Borg ever took place. A version of General Korok is alive in both the Alpha and Delta Quadrants simultaneously, one free, and one a Borg drone.

(Theory by Bond, James Bond)