A closer look at the Avengers 4 toy leak that revealed new costumes for Thor and Rocket Raccoon signals the remaining heroes may have larger concerns than Thanos in the Marvel Studios sequel.
The text on the back of the packaging reads, "The Asgardian Thor wields the mighty Stormbreaker in his battle against new foes. [...] Rocket teams up with a new crew to guard the galaxy from an even greater threat." Although vague, that description indicates not only additional villains, but ones perhaps greater than the Mad Titan. Considering that, with the Infinity Gauntlet, he possessed the power to wipe out half the life in the universe, that's certainly saying something.
Some have theorized that Annihilus, a Fantastic Four villain from the Negative Zone, could fit the bill. Another thing to note is that Rocket is working with new allies to "guard the galaxy." Considering he is included with the toy, Thor is a likely among them. Following the disappearance of every other Guardian of the Galaxy, the notion that Rocket is operating with a new team could lend credence to the rumor that Avengers 4 takes place five years after Avengers: Infinity War.
The toy in question has been the subject of much speculation, leading to theories about Hank Pym's involvement and Rocket officially joining the Avengers.
The sequel to Avengers: Infinity War will release on May 3, 2019. Directed by Joe and Anthony Russo, the film stars Robert Downey Jr., Josh Brolin, Mark Ruffalo, Tom Hiddleston, Chris Evans, Chris Hemsworth, Jeremy Renner, Chris Pratt, Elizabeth Olsen, Sebastian Stan, Benedict Cumberbatch, Paul Bettany, Samuel L. Jackson, Cobie Smulders, Benedict Wong, Zoe Saldana, Karen Gillan, Vin Diesel, Dave Bautista, Pom Klementieff, Scarlett Johansson, Paul Rudd, Evangeline Lily, Tom Holland and Anthony Mackie.
(via Comic Book Movie)