There are basically three races which dominate the future of this universe: The Borg, The Predators and the Aliens.
Most of you have seen what a confrontation between a Predator and an Alien looks like. The outcome is unpredictable.
There remains however one more force, the Borg, which is unfathomable in its power.
A confrontation between a Predator and a Borg or between an Alien and a Borg can be analyzed based on some simple observations:
Predators are carnal. Aliens are biomechanical, thus also part carnal. A Borg, although a human based cyborg, can assimilate theories about relativity, thus can travel back and forth in time, eventually rendering the weapons of the Predators and Aliens useless.
An initial confrontation of Predators and the Borg will undoubtedly have initially major casualties on the side of the Borg, as the Predators try to fend them off with their technology and weaponry. While the Borg are being destroyed individually, they communicate the information of the Predator technology through the Hive Mind back to the Borg Cube.
The Hive immediately starts manufacturing devices which bend time and space, and supplies with those the remaining army of the Borg, who then will attempt to teletransport again into the Predator ship. This second time, the weapons of the Predators will be utterly ineffective against the Borg, who every time a Predator projectile is launched against them, they switch their time domains, approaching the Predators from a parallel universe which is unaffected by carnal weapons.
Thus, if the Borg Cube EVER, manages to tractor beam a Predator spaceship, they will not only assimilate all the existing Predator technology, but they will also assimilate the Predators themselves. In short, the Predator ship will not survive. The Predators know this, that's why they don't ever approach this planet, except only as an emergency measure, to escape an attack on their spaceship, using their individual escape pods.
Something similar happens with the Alien life forms. While initially the Borg's curiosity is enough to warrant a visit to the planet with the Derelict spaceship upon receiving the warning signal from the ship, and allowing a couple of their individuals to host some Aliens, the emerging Aliens will have no additional tools to fight the rest of the Borg, because the latter can still switch realities and examine the Aliens from a parallel reality.
When the Aliens are examined thoroughly, the Hive mind of the Cube will isolate them and keep them as interesting specimens from which they can extract more information about the Derelict spaceship and its origin.
While Predators and Aliens respect each other and fear each other because the outcome from such a battle can be unpredictable, the Borg do not give a rat's ass about either one. All they want is to assimilate more information, so extreme caution should be applied when you invoke them.
The good news is, however, that the Borg are our future. Therefore they need us. When one is needed, one survives. When one is needed for all eternity, one survives for all eternity.
How are the Borg our future? They are our dreams. We created them. We dreamt of them inside The Matrix, while we were sleeping. We essentially created the ultimate force in the universe. You say, "we are not there yet". I say, details are unimportant. The moment the dream gets created, the rest is details.
In short, we construct our own future while we are dreaming inside The Matrix. But what IS The Matrix? It's us in this reality. Earth and all the goodies. That's the Borg Cube, you see. So, my fine gentlemen, you are all dreaming Borgs.
The Borg are the only creatures which can stand in front of the Demiurge and say: "We are here and there's nothing you can do about us. You either GIVE us Godhood, or we'll take it from you by force". Fortunately or unfortunately, the Demiurge is nowhere to be found, so we'll never know until we encounter Him.
Heh. That's why nothing ever dares to approach this planet or to communicate with us. We'll fuck them up the ass twentyfold.