I think the top comment on that vid was "hey looks like my crappy playthrough became canon!"
The whole aliens-conquered-earth angle threw me quite a bit because the entire end of previous game foreshadowed the aliens testing humanity to see if they would be able to endure a much greater threat than the ethereals.
Had a laugh at the snake men and then remembered that they were a thing way back when although I never actually played through the original games.
My biggest concern for sequels is always in the execution. Building off the strengths of the original while simultaneously expanding upon the core of the game and ironing out any rough spots can be quite the ordeal for a developer. Here's hoping for the best. So long as I can still have my Polish sniper cackle "HASTA LA VISTA, BABY!" from 2/3rds of the map away I'll probably be satisfied, though. Still, how is nation funding going to happen? Will it be possible to "lose" a nation due to panic/threat levels?
I heard Firaxis may have been in touch with the Long War people? Anyone else have any confirmation?
My best guess for the plot is that after humans showed their potential in the Temple Ship battle at the end of Enemy Unknown
, whatever force is commanding the aliens decided to come and add Earth to their collective.