Diggle’s unrealized Green Lantern future in the Arrowverse was a letdown for many, especially with Ramsey having been one of the Arrowverse’s foundational characters with his role as John Diggle. The advantage of DC movies and shows transitioning into a multiverse could nonetheless give Diggle a second chance to wield Green Lantern’s might. Even better, Diggle doing so as an ally of the Man of Steel on Superman & Lois season 3 could actively build upon the twist ending of season 2.
Diggle’s discovery of the box with the green glow inside in Arrow’s final episode set many minds racing that his transformation into the Arrowverse’s Green Lantern was right around the corner. However, while Stargirl debuted a Green Lantern, Diggle instead experienced headaches that he attributed to the mysterious green item in the box. The Flash season 8 finally resolved the box’s mystery, albeit in a way that turned Diggle away from any future with a Power Ring after consulting with Eobard Thawne (Tom Cavanagh) in his ARGUS prison cell.
Thawne unveiled that items such as the green box periodically appear to humans with the capacity to use their power. With Thawne’s help, Diggle opened the box and saw different versions of his life played out before his eyes. With the knowledge that such lives would come at the cost of Diggle leaving his family, he chose to turn down the alien power it presented, effectively ending any potential future for him as Green Lantern in the Arrowverse.