The world has ended on Agents of S.H.I.E.L.D. and a post-apocalyptic society has never been quite so literal. Our heroes were blasted through space and time and according to their new not-quite-friend Deke, Daisy literally quaked the Earth to smithereens with her powers. However, there is a little bit of hope for all four dimensions at play here in the form of a mystery. Where is Fitz on Agents Of S.H.I.E.L.D.? What's up with that postcard? He's not with the team, but he and Simmons are still connected.
Virgil, the "true believer" in Coulson that brings the team through the monolith, does not include Fitz in his time traveling people order for some reason — but tells Simmons that Fitz was thinking of her. First of all, it's wild that in the Marvel Cinematic Universe someone would start a cult around Coulson and not like Loki, or Hawkeye, or Aunt May. Second of all, that's rude and unhelpful, Virgil! Why would you leave Fitz out like that? He must be serving some kind of purpose on the "ground" that is the past on Earth. In fact, it was in trying to send a message back to Fitz on Earth that the team simultaneously discovered they were in the future in the first place.
He's definitely doing something. When the team escapes one Kree threat only to land in another, they encounter a vintage post card with four words: "Working on it. — Fitz." Is he working on trying to find them, get to them, or prevent the end of the planet? How did the message get there? How did he find out where and when they are? Why are Fitz and Simmons separated no matter what the mission or catastrophe is? This "curse" is truly unfair.
“He might be turning up in space sometime,” said Iain De Caestecker in an interview with TVLine. “But he’s not there right now…. That’s my answer, and I’m sticking to it.” Did anybody else think that Fitz was going to meet Jemma when she was taken by the Kree to become some kind of elite human servant? Her weird visions are suspicious, too. Simmons suspects that in the place in time they are now, Fitz has already lived his life and died — but maybe he'll find a way to meet up with them and maybe he already has.
At the moment following their departure however, Fitz is presumably on Earth trying to figure out where the team is and how he can save them. It takes his occasional role as "man in the chair," to borrow a term from Spider-Man: Homecoming, to a whole new level and dimension entirely. Hopefully he can also stop Daisy from destroying the planet while he's at it. The fact that he is still on Earth could cause some tension when the team finds out what Daisy allegedly did to it. The situation “raises the stakes so much,” Elizabeth Henstridge said in the same TVLine interview, “because when you think about everybody that’s not with us, what does that mean?”
Fitz is also likely still grabbling with what he became in the Framework. He very comfortably fell into the role of an evil Hydra boss, and that has to be scary to wake up from and realize. One interesting detail about the future is that Deke's virtual reality vacation bar is based on the Framework technology, which means it somehow lasted for many years. Entertainment Weekly theorized that the Framework may be a way to communicate with Fitz in the past, which is a decent possibility.
At least Fitz is "working on it." That much we know. This whole situation is like Firefly meets Battlestar Galactica meets The Hunger Games with probably about two dozen other science fiction homages in there, from Logan's Run to Snowpiercer. It's incredibly fun to watch the S.H.I.E.L.D. agents navigate this unfamiliar territory where they don't have any kind of familiarity with the societal rules or power. Whether Fitz gets to join in or not, there's absolutely no way of knowing where this is going.