But Kynge Pellynore bare the wyte of the dethe of Kynge Lott, wherefore Sir Gawain revenged the deth of hys fadir the tenthe yere aftir he was made knyght, and slew Kynge Pellynore hys owne hondis. (51.24-27)
Even in this moment, when Pellynore’s death is still far in the future, our narrator still brings it up. Regardless of whether or not he’s some sort of psychic, our narrator’s mention of this tells us that this is a pretty important part of the story. This particular blood feud is as much a part of the Round Table’s fall as Gwenyvere’s affair with Launcelot, so the narrator drops hints, even this early in the story.