With Smallville's Tom Welling being open to returning to the Superman role in Robert Pattinson's The Batman, it actually wouldn't be impossible after the events of Arrowverse's Crisis on Infinite Earths. One of Warner Bros.'s most prominent DC properties ever produced is Smallville, the Superman prequel series that ran for ten seasons and paved the way for the comic book TV genre to be what it is today. Back in the early 2000s, Smallville was pretty much the only major superhero TV show as it told Clark Kent's origin story before becoming the Man of Steel. After the series ended in 2011, Welling returned with his co-star Erica Durance, who played Lois Lane, for the 2019 Arrowverse crossover event, Crisis on Infinite Earths.
Not only did the five-part crossover established Smallville to come from Earth-167, but it revealed Clark had given up his Kryptonian powers to live everyday life with his wife and daughters. While Earth-167 was destroyed off-screen, the Smallville universe still exists in the new Arrowverse Multiverse, as confirmed by executive producer Marc Guggenheim. Even though Smallville will never return regularly, it seems Welling is game to reprise his role again if asked. In a recent interview, Welling shared he was open to being the Superman in Pattinson's The Batman universe, as the two actors are friends in real life. It would likely not lead to Welling being a significant presence or suddenly having a film franchise co-existing with Matt Reeves' The Batman reboot.
If anything, it would probably only be as a supporting character or a cameo appearance, similarly to Welling's Crisis spot. Whether it happens or not, it is actually not impossible for Smallville's version of Superman to be part of The Batman universe, especially after Crisis on Infinite Earths. For starters, even if Clark no longer had powers during Crisis, who is to say that is still the case after his Earth was revived? While there have been rumblings about The Batman being set on Earth-2, it's likely not that specific Earth designation. Based on The Batman set photos, Superman definitely exists in some capacity. An extra was spotted wearing a Superman suit for a Halloween party while an article from The Gotham Times has referred to a mystery savior in Metropolis.
In one way or another, Superman is part of The Batman's continuity, which paves the way for Smallville's Clark to exist in that world too. Clark did befriend Batman in the Smallville season 11 tie-in comic, which was said to be canon by Guggenheim when Welling was set to reprise his role for the Arrowverse crossover. But it became evident Smallville season 11 wasn't necessarily being counted after all. Clark seemed utterly out of the loop regarding the Multiverse, despite the comic having done its own Crisis on Infinite Earths adaptation, which also involved Monitors. If Welling's Superman were to somehow be in Pattinson's universe, it wouldn't be a stretch for them to ignore Clark having met Bruce Wayne in Smallville season 11.
Whether or not it will actually happen is up to the creative team if they want to bring Welling's Superman from Smallville into The Batman universe. If Welling would make an appearance, it wouldn't be until the sequels. The upcoming film will be tackling Bruce's second year as a crime fighter, which would be ruined if The Batman suddenly began adding DC cameos. But it is fun knowing that Welling and Pattinson are buddies, with the former also being open to reprising his role as Smallville's Superman in The Batman, which by all means can happen after Crisis on Infinite Earths.
