Undoubtedly, it was a glimpse into the future. Age of Ultron opens with Tony Stark seeing a picture of the World being overtaken by Chitauri and a mass of fallen Avengers. Tony wasn't the only one who had visions, the premonition of what was to come was also experienced by other 4 OG avengers, these visions clearly connected with what happed in Infinity War and Endgame. For Tony it was nightmare, he was shown that what could happen if he did not volunteer. The very first glimpse we get is of Hulk, who no one thought could be defeated, despite the fact that he was completely decimated. However, he was visibly breathing, indicating that he wasn't dead. This hinted at what would happen in Infinity War, specifically, Hulk losing the fight to Thanos. Thor is lying down with his eyes closed, implying that he is unconscious rather than dead. You could also argue that Mjolnir is just out of reach for Thor, which could be a hint as to how he lost Mjolnir in Thor: Ragnarok, although that...