Avengers 4 fan theories have been doing the rounds online non-stop since the credits finally stopped rolling on Infinity War, but there was always one that stood out - that of the surviving Avengers using the Quantum Realm to defeat Thanos. Those who've seen Ant Man and the Wasp will already know that the setting is used heavily in that film, and with Scott Lang revealed to be trapped in it at the ending, it's clear that he's going to have to find a way out somehow.
Enter the latest round of Avengers 4 leaks, which show Thor and Rocket Raccoon in new grey costumes that look as though they were built specifically for extreme conditions. Throw in the fact that both characters are regular spacefarers, along with the knowledge that they retain their old suits for a certain period of the film (as was revealed by concept art), and it looks increasingly likely that they'll be heading somewhere hazardous - the most likely destination being the Quantum Realm itself.
As you can see from the above image, Thor and Rocket are wearing grey armour with the Avengers logo in full display, and it's been said that their teammates will wear a similar garb during a period in the film where they too head to the Quantum Realm, potentially in the hope of encountering a time vortex. A brief glimpse of Captain America's white suit can also be seen to the lower right of the image.
This is all just speculation of course, but given how the Avengers have never worn the same uniform before, it seems likely that this design was created for them to head to the Quantum Realm, given how similar it looks to the suit worn by Hank Pym when he ventured there in Ant Man and the Wasp. Will it help them defeat Thanos? Potentially, but with talk of more villains potentially entering the fray, Avengers 4 looks just as likely to subvert expectations as Infinity War did back in April.