When the original Matrix trilogy ended back in 2003, the Wachowskis made it clear they were interested in passing the future of the franchise--and its lore--to fans through the Matrix Online MMO game. The game has long since ended, but a moment included in the first full trailer for The Matrix Resurrections appears to suggest it's still being considered canon.
Major spoilers for the films and The Matrix Online to follow, and yes, that is actually important!
It's a blink-and-you'll-miss-it moment in the first Matrix Resurrections trailer, but you can very briefly see Neo's body in a post-Revolutions moment at roughly 12 seconds. His eye is clearly burned away, as it was in the film following his encounter with Bane, and he's being worked on by a few spider-like Sentinel machines.
"I didn't say it would be easy, Neo. I just said it would be the truth."Now, what does any of this have to do with The Matrix Online?
Well, the Wachowskis didn't want the story for The Matrix to end with the third film. Instead, the MMO acted as a continuation, and one of the major story threads involved Morpheus' frustration that the machines had not yet returned Neo's body. This led to him committing attacks in the Matrix, planting "code bombs" to wake up and confuse those still connected until he was ultimately (apparently) assassinated.
Based on the shot from the trailer, it appears the machines never did give back Neo's body. This isn't a guarantee that Lana Wachowski is treating the game as 100% canonical, but given her statements in the past, it could certainly be the case. If so, it would help to explain why Laurence Fishburne isn't in the film, though the reason for Carrie-Anne Moss' involvement remains a mystery, given that she died in the real world near the end of the third film. Neo did, as well, but the Oracle's prophecy that he would one day return does seem to account for his, well, resurrection.
We'll just have to wait and see if this is all true, of course. The Matrix Resurrections releases on December 22, both in theaters and via HBO Max's ad-free tier.