Since Barry found out that there is a future where Savitar kills Iris on The Flash, Team Flash has been dealing with it in different ways. In The Flash "Dead or Alive" Cisco, Caitlin, and newbie Julian worked on creating a 3-D model of what Barry saw, along with calculations to figure out how fast Barry would have to run in order to save Iris. Meanwhile, desperate to leave a mark before she maybe dies in four months, Iris threw herself into her work, and, with Wally's help, into the path of a dangerous arms dealer. Helping Iris with her reckless, journalistic mission might not have been Wally's best idea, but it did force Barry to consider a new possibility. Will Wally save Iris on The Flash?
Now that Barry is comfortable taking Wally along on missions, Kid Flash is becoming a superhero. Not only is Wally running faster, he's improving far more quickly than Barry ever did. And, though he was foolish in helping Iris get her story, he was quick enough to save her, and there's no doubt he'd do it again. And, try as he might, Barry simply isn't going to be able to get fast enough to save Iris in the four months they have left. But Wally might.
Kid Flash could be the key to saving Iris. If he can get fast enough in time, then he can get Iris out of Savitar's clutches, and Barry can defeat the so-called god of speed. Two speedsters are always better then one.