I'm guessing that preview is from early in the series, but if it's a glimpse of the final battle, then I think we all know what happens -- Cap defeats Doom and then unleashes the PF back to the cosmos. I trust the story won't be that predictable, but on the other hand it was rather predictable that they'd use the PF in this fashion. Kind of saw it coming after Thanos or Thanos, Jr. had the PF.