Rick Jones, the human temporarily bestowed with “heightened mental power[s]” during the Kree-Skrull war, perished during the war. He had been instrumental in “ending the war”. Thus in this reality, the war wages on as the Avengers try to save Earth.
The magnitude of this galactic war does not go unnoticed by the Fantastic Four. Professor Xavier contacts Mr Fantastic and offers his help. While the Fantastic Four head off to join the Avengers in the battle, Xavier will “seek others to aid [their] cause”.