A full on alien onslaught at this rather weak technological juncture in our history would appear to result in complete extinction, or enslavement of the human race! Undoubtedly had we not wasted countless centuries in superstitious ignorance, coupled with stifling tyrannical regimes, we would be exploring the stars now! Even the top secret technology that various governments possess, decades in advance of our current society, wouldn’t be enough to defend Earth from an extraterrestrial invasion force. Fortunately we have the world of the supernatural on our side for the most part since Earth is an enchanted planet!
A plethora of higher dimensional beings such as Gods, Angels, and Demons would probably continue to keep their low profiles. However they might funnel more metaphysical energy to practitioners of magic who would fight against the ET menace. Unfortunately top flight psychics, seers, and mystics have seen our technology coming up with defenses against magic in the next 1000 years or so! Great for us in the future but regrettably this means aliens might have defenses against Sorcerers, Wizards, Witches, and Warlocks! Plausibly the forces of darkness, and light might come together to defend Earth, and humanity for their own reasons. On the ground we could see various forces of evil such as vampires defending us if only to protect their prey! Of course if the aliens are backed by demons, or other dark higher dimensionals then we wouldn’t see as many dark sourced anti-heroes.
There’s also the possibility of the extraterrestrials being so powerful that they could extinguish all life instantly with some kind of death ray that would only leave core elements behind for mining purposes. For reasons unknown they could also disintegrate the entire earth with some diabolical doomsday device! In both those cases the spirit of the Earth, Goddess Gaia, would probably defend her body from being obliterated. Any non-interference agreement, such as the Supernatural Secrecy Pact, would go right out the window if she’s talking about her own life! Certainly the immense pantheons of nature deities would come to her aid as well! Another interesting scenario would be if the extraterrestrials planet had a sapient spirit who backed their planetary conquests, and would launch a simultaneous attack on Mother Earth? Perhaps an entity like the God of War Mars!
Extremely gifted long range psychics have predicted we may see some close ET invasion calls during the next 1000 years. Thankfully we will somehow barely squeak past being annihilated, and enslaved!