In Kingdom Hearts 4, based on what little has been shown far, Donald and Goofy are searching for Sora after the last game took a dramatic turn, with him sacrificing everything to save Kairi once again. While Kairi was safely restored and brought home to the Destiny Islands, it seems that Sora had to pay the ultimate price and is currently lost to a "fictional world." While King Mickey warned Sora that this might be the case, the hero's friends haven't given up on finding him and bringing him home.
In Kingdom Hearts: Melody of Memory, Kairi, Riku, and Cinderella's Fairy God Mother went to the Final World to enlist the help of a formless star to create a portal to Quadratum, where Sora supposedly resides at the start of Kingdom Hearts 4. While Riku sets off to explore Quadratum, Donald and Goofy were tasked with assisting the search by updating Sora's friends across worlds. Through the dog and duck's journey, a series staple may be allowed to co-exist alongside the more realistic narrative found in KH4.
Kingdom Hearts 4's Realistic Unreality Storyline
Now that Master Xehanort has been defeated and the "Dark Seeker" arc has officially concluded, it's understandable that the next chapter of Kingdom Hearts would broach new territory that the series has yet to explore. This time, Sora is trapped on the "other side" outside his own reality. Experts like Ansem the Wise have considered this to be a type of "unreality," or even dwelling in the realm of "fiction."
Ironically enough, the "fictional world" of Quadratum is incredibly like the real world. Quadratum is very heavily based on the Shibuya ward in Tokyo, Japan, where fans have even used to the real location to know where Sora lives in the first Kingdom Hearts 4 trailer. With this interesting realistic setting, however, there isn't much of a chance for Sora to explore the normal Disney worlds that the series has been known for. Donald and Goofy could fix that, though.
Donald and Goofy Should Traverse the Disney Worlds in Kingdom Hearts 4
At the end of Kingdom Hearts: Melody of Memory, Donald and Goofy are ordered by Master Yen Sid to spread the word of Sora's whereabouts to those in Radiant Garden, the Land of Departure, and Twilight Town, as they have been conducting their own searches into leads about the missing Keyblade wielder. This puts the magician and the guard in the perfect position to travel around the Lanes Between and maybe discover a lead of their own. This might inspire the duo to go looking for their missing partner in the other Disney worlds.
This could end up creating a wonderful balance in that Sora would be allowed to explore all new original worlds, while Donald and Goofy poke their heads into the different cartoony worlds, acting as breathers against whatever deeper, likely darker story that lurks within Kingdom Hearts 4's new narrative. It would be a great way for Square Enix to get rid of what otherwise would be an incredible clash while also possibly giving Disney worlds more plot relevance.
As great as this idea might seem, there's a strong chance that KH4 may go in a different direction. Not much is known about Kingdom Hearts 4 just yet, but previous franchise trends suggest that the B plot storyline may fall to Riku as it did in Dream Drop Distance. However, Kingdom Hearts has been one of the trickiest gaming franchises to predict, and Donald and Goofy possibly paying a visit to Olympus Coliseum and its Underworld wouldn't be teased if it wasn't important. Fans will just need to stay tuned for future announcements to get a better idea of what to expect.
Kingdom Hearts 4 is in development.