With big wins for 20th Century Fox in Logan and Deadpool, the two R-rated editions of the X-Men franchise, the studio has clearly hit on something big. Even X-Men: Apocalypse, while it landed softly with critics and in the U.S. box office, hit it big worldwide, still currently holding onto third in the 10-film history (though Logan continues to creep up on it).
While the R rating is part of the formula for success for Deadpool and Logan due to the nature of the films and their source material, that’s not what Fox can take forward into most of the other X-franchise films, or even further into that other Marvel property they’re hanging onto with what many fans see as increased desperation: Fantastic Four. However, they can learn from these successes to save the languishing franchise, and maybe even launch it into a true franchise of its own.
While the original pair of Fantastic Four films quite frankly didn’t get much right, they did at least try to use the source material for a few things, like the costumes, the origin and even pretty good reparté between The Thing and Human Torch. That's the biggest lesson that Fox can take from Logan and Deadpool to Fantastic Four: Don't be scared to use the Marvel Comics that it came from as inspiration! While neither of the FF films directly adapted a Marvel story, they did focus on keeping the characterization and tone that the comics made popular when they hit the big screen, and that made all the difference in both critical and audience response. You can do a direct one-to-one comparison, after all, since both Logan and Wade Wilson were drastically misused and mischaracterized in X-Men Origins: Wolverine.
Start from the comics, start with the characters, and move up from there.
So how do we apply that to Fantastic Four? It's literally in the name: focus on the Fantastic, and the family of Four. The plots of the three attempts at big-screen films featuring the First Family of Marvel Comics didn't go nearly far enough. The best Fantastic Four comic book stories feature soaring adventures, often through space and even time. They see space gods and time traveling despots, they fight monstrous dragons and underground armies, and they always do it together.
The core group of Sue, Reed, Ben and Johnny need to feel instantly and completely like a family. Skip the origin story and just show us four people who clearly love each other and work together as a cohesive unit. This group should practically read one another's minds, and the way they move, whether fighting enemies or simply conversing and living their lives, should be more of a well-oiled machine than any Avengers, X-Men or Justice League team could ever be.
So could Fox pull this off without a complete reboot and recasting? Possibly, though Michael B. Jordan already moving on to another Marvel Comics role (he's playing the villain Eric Killmonger in Black Panther for Marvel Studios) isn't a great sign for the future of the current F4. With the dismal tone and disjointed story of the 2015 film, it wasn't even possible for fans to see whether they had the potential for that sort of chemistry.
Instead, it's probably best to recast (again) but not really reboot so much as simply fast-forward. Start with a slightly older team, more age-appropriate to the comics, and a team that's clearly been working with each other and their powers for some time. Then you take them on a fantastic voyage, you use literally any villain besides Doctor Doom and use them directly in their comic book form, and you're off to the races.
A common refrain from the superhero fan community (and critics) is that the best Fantastic Four movie was Pixar's The Incredibles (2004), and it's a valid point. Even without quite as much flash as I'm suggesting here, it got those two points that make Fantastic Four a fan-favorite team despite Marvel not even publishing it anymore: the sense of the fantastic, and closeness of family.
Of course, many fans have another "simple" solution: give this team back to Marvel Studios, and let them figure it out. While Fox and Marvel TV have been working closely together lately on their various X-Men series, there's still no indication that things on the film studio side have warmed in any way, so unfortunately if you're hoping for another try at the Fantastic Four (and their related characters) on the silver screen, you'll probably have to wait for Fox to figure it out.
At least now, thanks to Deadpool and Logan, they have a lesson learned that they can take forward into the franchise's future.