John Cena appears to have found a long-term home in the DCEU as Peacemaker. After making his debut in last year's The Suicide Squad, Cena reprised his role as the titular character in the first DCEU series ever. Following the success of Peacemaker's first season, HBO confirmed that a second one was coming and it appears that Cena is open to seeing fellow WWE superstar, Dwayne "The Rock" Johnson, make an appearance as Black Adam in the eight-episode follow-up season.
In a People magazine interview, Cena was very open-minded when asked about a potential Black Adam cameo. In particular, Cena mentioned that anything can happen in the DCEU and shared how he'd love to get a chance to work with Johnson outside of the WWE. Unfortunately, Cena clarified that he doesn't have any creative control over Peacemaker, so he can't exactly ask James Gunn or Warner Bros executives to bring in Johnson even if it's only for a brief cameo.
Then again, if Cena is open to it and we assume that Johnson is too, why shouldn't it happen?