In a new episode of DC All Access, actor Grant Gustin gave some more details on how the new timeline will affect Barry and his memory of the past two seasons. "Barry's the only one who knows that the timeline is different," Gustin explained. "And his memories are gradually being replaced by memories of graduating high school and college, his moments with his family, and when he realizes that those memories are replacing other memories, that's when he starts to realize how selfish of a decision this was."
But memory loss won't be Barry's only problem; apparently his powers will also begin to disappear. "It means he's forgetting his powers, too. He's having a full Back to the Future moment, his hand disappearing in front of him,"