So as you may or may not know, at the end of Mortal Kombat X, Raiden gave Shinnok's head to Liu Kang and Kitana, the new rulers of the NetherRealm. Raiden told them he would show no mercy to anyone who threatened EarthRealm, and looked like his dark self from MK: Deception or Armageddon.
This was a hint towards the future of the series, and indeed it seems that Raiden may be the star of Mortal Kombat XI's story. So be prepared to see the thunder God as the main villain of MKXI.
According to the same rumours, XI will be feature the most expansive story mode yet, with 20 Chapters, clocking in around the 12 hour mark! That's more than double the length of MKX!
It sounds like the team at NetherRealm is doubling down on the story, after high praise for said mode in both MKX and Injustice 2.