Independence Day 2. What might have happened in-between

This was in reply to a similar post in IMDb, a post which speculated on what might have happened in the 15-odd years on Earth since the events set in "Independence Day" (1996). Because IMDb forums for a movie or personality are cleaned up from time to time, I've decided to simultaneously publish this here along with the reply on IMDb.

Disclaimer: This blogpost does not contain spoilers to the movie, because I am not aware of its actual content.

My favourite ideas revolve around relations between humans and surviving aliens from the first war.

Of the surviving party (parties), there would be at least two or three 'factions', put this way:
* Those that want to destroy humanity and much of Earth and reconnect with whatever future mothership comes. These would be fighters and their ilk (the alien hard-liners);
* Those who somehow automagically decide that humans are worth something, too, and the Earth preserving.
* And maybe those that kinda-sorta like Earth, but not humans, only that they can't do much about it. The undecided (?).

It's possible that maybe one of the city-ships somehow survived to the point that it's established a state-like territory on its own, but that the ship itself is unable to become airborne. Maybe there are more than one and each has formed a different faction and attitude towards Earth and humanity.

Then the structure of the alien society: What was it like before, during, and after the invasion?

Then the very serious problems around whether and how to integrate surviving aliens into society (à la "Alien Nation", but it wouldn't work out like that anyway) — Because if we're better than them, then we can't just kill them all off. I'm aware it's very pacifist and stuff.

And then about how humans treat or mistreat the surviving aliens — look at Guantánamo; and would there even be trials? Does the whole species need to be convicted, or just the ones who set the agenda? How do you find out the surviving alien leaders (given that they all seem to look alike), and whether there are any, if the social structure and ways of communication are so different?

It's likely that humans and (former) invaders would mostly feel mutually repelled by one another and keep up some form of segregation ("District 9"). Would be interesting to know if that's in the new movie.

Then all the issues wrt biocontamination. Organic as they all are, there must be observable changes in Earth's nature. Did the first strikes also hit nuclear plants and was there any fallout and thus any possibility of a nuclear winter? Then I'd imagine the use of cars with internal combustion engines has perhaps lessened alot first due to destruction of major population centres and because of new technology.

The idea of a third and fourth species is also very intersting, given that a large explosion in space can be noticed by a civilization with at least similar advancement.

Oh, the "Pocahontas" scenario of two kindred spirits meeting one another would never work. No, no. But I wouldn't rule out several accidental hybrids. There's a possibility that if some alien surviors managed to form a workable faction within the confines of their previous social structure, then they might have made several experiments with human survivors until releasing one or more, or even a group of human-alien hybrids. And I suppose those in turn would have very dangerous properties. Maybe alien-human infiltrators.

Then what has happened to different human societies on Earth. Suppose some states rebuild and develop military technology, but at the cost of freedom. Some countries decide to keep individual freedoms, but maybe or maybe not risk being less secure. Or countries who decide not to adopt alien technologies and develop native technologies (Not Invented Here syndrome), or countries that don't want to sacrifice freedoms and develop slower and on their own pace compared to those that might sacrifice freedoms and might want to adopt all the latest alien tech.