This one isn't a surprise, but developer 343 Industries have confirmed that they aren't bringing Halo 6 to E3 this year. In a post on reddit, 343 community manager Brian Jarrard (aka sk7ch343) decided to crush some fans' dreams for this year's electronic entertainment expo, saying that while the studio will have something at E3, it won't be tied to Halo 6. That doesn't mean we won't see some Halo 6 teases during the Microsoft show, but it's likely that 343 are instead going to focus on DLC for Halo Wars 2.
That, or we're getting a big-budget Halo film. Either option would be something we'd expect to see at E3 this year.
"I'll slip into my Dreamcrusher persona for a minute in the name of realistic expectations: We've said this already but we'll have a little something at E3 but it's not related to the next major entry in the franchise," Jarrard said.
What we do know about Halo 6 so far is a bit sketchy. The game will prominently feature Master Chief as Executive Producer Kiki Wolfkill and Franchise Director Frank O'Connor promised in a recent interview, and as Studio Head Bonnie Ross confirmed at DICE this year, it will have split-screen multiplayer.
Given the recent turnovers at 343 Industries, including Halo head man Dan Ayoub who has left 343 for another division in Microsoft, it's very likely that 343 Industries' plans for E3 are rather low-key.