Well, since this is a 2-cours TV anime by Imaishi and Nakashima, I expect the 1st cour to be Ryuuko vs the Student Council, while the 2nd cour has Ryuuko and the Student Council being allies to take out the actual BIG BAD.
Satsuki is looking to be the Lord Genome of this series. Still a long way to know who's the Anti-Spiral here.