Despite Ezra Miller's recent assurances that there was no major delay looming for The Flash, and despite the fact that it's lost its second director in under seven months, the writing on the wall isn't hard to see. Without a finalized script, and without a director announced, there's very little chance they can get this movie made in the original time they'd slotted for it- or released on the date they'd planned.
Meanwhile, Aquaman has been chugging along on a very reliable path. James Wan has been committed to directing the film for a while; Star Jason Momoa has been game to create a big splash with his new take on Aquaman for quite some time; And a recent move by Paramount Pictures may have just telegraphed what many of us have been thinking for a while:
Aquaman may get moved forward, now that The Flash is likely to get pushed back.
The aforementioned move by Paramount is their decision to release Mission: Impossible 6 on July 27, 2018- the same date Warner Bros. had set for Aquaman. This is a fairly unprecedented move. Most major studios, with their intimate knowledge of what their competitors are working on, avoid this kind of situation at all costs. You never want two competing tentpoles to open on the same date, especially when they'd seemingly court the same audience. It's one thing to counter-program (releasing an animated children's movie, or a mature rom-com opposite a superhero flick, for example), and it's another thing entirely to open two high-wattage PG-13 action movies on the same day.
So why would Paramount do this? Probably because their little birds have told them that Aquaman will no longer be coming out on July 27, 2018. That's why.
And considering there's been no talk of drama or tumultuousness on the Aquaman front, the easier assumption to make is that it's coming out sooner than expected. Not later.
To be clear, this doesn't mean that we can expect Aquaman to come out in The Flash's original March 16, 2018 slot. That'd be pretty impossible to pull off at this point, since the film won't even officially enter pre-production until next month. But it's entirely possible that Aquaman may get the same release window as 2017's Wonder Woman and come out on June 1, 2018.
A June 1 release would give Avengers: Infinity War (May 4) almost a full month to finish up its run, and put a month between Aquaman and Ant-Man And The Wasp (July 6). It's closest competitor would be the following week's untitled Transformers: Bumblebee Spinoff (June 8). Considering Warner Bros. opened Superman Returns a week before Pirates Of The Caribbean: Dead Man's Chest in June of 2006, the studio doesn't seem worried about that kind of contest.
We'll see how it all pans out, but considering Paramount has now staked a claim to July 27, 2018, we can expect Warner Bros. to announce what they're going to do with Aquaman pretty soon.