While it still hasn't been confirmed, Deadpool 3 is expected to take the Merc with the Mouth and Wolverine into the Multiverse. That's surely going to result in them being left stranded on Earth-616 when all is said and done, likely going some way in setting the stage for Avengers: Secret Wars.
However, the movie may involve the introduction of an unexpected location from the comic books we didn't expect to see on screen for at least a few more years. Scooper Daniel Richtman has strongly hinted we'll see Secret Wars' Battleworld in the upcoming Marvel Studios threequel.
The original Battleworld was constructed in Marvel Super Heroes Secret Wars after The Beyonder took pieces from hundreds of worlds, including Earth, to create an arena for his "Secret Wars."
The later version of Battleworld was a patchwork world made from the remnants of destroyed realities following the Multiverse's collapse due to incursions. It was created by Doctor Doom after he stole the power of the Beyonders, secretly via the Molecule Man.
Doom ruled Battleworld for eight years as "God Emperor" before it was destroyed when the Molecule Man gave the power of the Beyonders to Reed Richards.
We don't know how this planet will be incorporated into Deadpool 3, but it could be in a similar manner to The Void in Loki. It's a little strange for it to be used now as it pre-empts the planet's likely creation in Marvel Studios' Secret Wars movie; one rumour suggests The Beyonder - another Kang Variant - creates a new reality/Sacred Timeline in his image, similar to Doom.
Of course, with rumours swirling that Earth-838 has been conquered following the Scarlet Witch's slaughter of the Illuminati, it's possible that rather than a full-blown Battleworld, we'll simply see something akin to it.
Alongside Ryan Reynolds and Hugh Jackman, Deadpool franchise vets Karan Soni (Dopinder), Leslie Uggams (Blind Al), Morena Baccarin (Vanessa), Stefan Kapicic (Colossus), Brianna Hildebrand (Negasonic Teenage Warhead), Shioli Kutsuna (Yukio), and Rob Delaney (Peter) are all set to return in this threequel.
Emma Corrin is expected to play Cassandra Nova, while Matthew Macfadyen will likely take on the role of a TVA agent named Paradox. It's also been confirmed that Jennifer Garner will reprise her role as Elektra, with Ben Affleck, James Marsden, Patrick Stewart, and Ian McKellen among the many names rumoured to appear.
While a delay due to the ongoing SAG-AFTRA and WGA strikes is possible, Deadpool 3 is currently set to be released in theaters on May 3, 2024.