Ever since the first movie in 2000, the lynchpins of the X-Men franchise have been Magneto and Professor X. Wolverine may be the most popular character and Hugh Jackman's final movie in the role, Logan, is undeniably the end of an era, but it was Erik Lechner and Charles Xavier who served as the series bedrock.
The first trilogy showed their classic ideological divide, with Ian McKellen and Patrick Stewart bringing gravitas to the comic book adaptation and overseeing the younger cast, while the prequel films had Michael Fassbender and James McAvoy fill in the backstory of their love-hate friendship (through a bit of crossover time travel rejigging along the way). As it stands, all six of the main series X-Men films have hinged on these two characters, and Stewart further appeared in two of the three Wolverine films. That's a lot of movies on a similar topic, and so it looks like the series is about to mix things up.
Speaking to Vanity Fair, X-Men super producer Lauren Shuler Donner, who has worked on every movie in the series, talked about the future of the franchise and said the Magneto-Professor X dichotomy won't be as essential going forward:
"We cannot, once again, explore the Erik/Charles dynamic."
Donner went on to state that the characters were “always essential” to X-Men but “there are other stories to tell.” Indeed, The future of the series post-Logan is, as it stands, pretty stacked; Deadpool 2 is next in line, with a teaser playing alongside Wolverine 3, and production is set to begin soon on both main series entry Supernova and spin-off New Mutants. James McAvoy is rumored to be returning as Professor X in the latter two - it's currently unknown if Fassbender is done with the series or not - so it seems that while their friendship won't be a driving force, the characters will remain.
This is overall good news. The opposed frenemies seem to have run their narrative course - each appearance tended to ride on the same basic idea and, while First Class went back to show its origins, now that has grown tired; Apocalypse, in particular, took things too far, with Magneto redeemed after siding briefly with the titular first mutant and parting with Charles as friends (despite him killing millions). That movie wasn't well received, and one of the biggest things its failure highlighted was that many people wanted new things from the X-Men.
There's definitely more to Charles and Erik in the comics than this single relationship, and Logan showed this obliquely by having Patrick Stewart plays a senile, nonagenarian version of his usually reserved telepath. While it's a shame there'll be less of these two characters' always-fun interactions, moving on is something that can only help the franchise grow.
Source: Vanity Fair
