If things keep going the way they've been going for the team, the future on The Flash will not be a bright one. Barry travels to the future in "The Once and Future Flash" hoping to find clues on how to save Iris' life and defeat Savitar, and what he sees is pretty depressing. However, Barry's trip isn't all doom and gloom: he also gets a lead on defeating Savitar from his future self. Future Barry is the key to defeating Savitar on The Flash, but it might not be enough to save Iris.
In the future — 2024 to be exact — Iris' death has destroyed Team Flash. Barry, now with long hair, lives his life in the Time Vault, while Joe takes care of a catatonic Wally, and Cisco sits in STAR Labs all alone. Caitlin, meanwhile, has fully transformed into Killer Frost and she's locked in a cell. Most members of the team are either unwilling or unable to help Barry, and Caitlin refuses to tell him Savitar's identity. But the trip isn't a complete waste of time. Barry leaves with a gift from Future Barry: a flash drive of sorts that, according to Future Barry, holds all the information he has on how to trap Savitar in the Speed Force. The only problem is that Savitar's prison was created by physicist Tracy Brand four years earlier — meaning four years after Iris' death.
The hard drive contains Tracy's information and her research, which is pretty much impossible for Future Barry to understand, let alone a Barry from four years before the technology is actually invented. Still, finding Tracy and getting her to look at the research is the best (and only) lead they have to defeating Savitar and saving Iris. Maybe this time around, Barry will be able to change his future yet again.