Titans is set to return for its third season, and the trailer may have hinted to Dick Grayson donning the cowl of Batman. Season 3 will hit HBO Max on August 12th, and will be heavy on the character transitions seen throughout the show, with the second Robin Jason Todd, played by Curran Walters, finally being consumed by his dark side to go from Robin to Red Hood, while Jay Lycurgo will join the show as the third Robin, Tim Drake. Season 3 also follows up on Dick's own transition from Robin to Nightwing in season 2, and there's a possibility that season 3 could see him take up his mentor's mantle as the Dark Knight.
Season 3's trailer includes a snippet of Iain Glen's Bruce Wayne saying to Dick "It's over for me. Be a better Batman". This line also seems to tie into the merciless crowbar beating that Jason will endure in season 3, a crowbar seen on the floor just before Bruce admonishes Dick to be better than him. In contrast to Dick simply leading the Titans in a way to rectify Bruce's failures, there are a few reasons why this could indicate that alongside Jason becoming Red Hood, Dick could suit up as the Caped Crusader in season 3.
For starters, this isn't the only hint of season 3 declaring Bruce a failure as Batman in the trailer, with the line "Bruce was a psychopath, using fear to control everyone". Season 1 had also made Dick's own falling out with Bruce very clear early on with his "F--- Batman" line in the very first episode. Though Dick and Bruce make amends in season 2, season 3 might follow the path of declaring Titans' take on Bruce Wayne as having failed to embody a true hero, with Dick as the show's lead to be the man capable of being the Batman Bruce never was.
As already stated, Titans has also been heavily devoted to the Robin characters moving from one costumed alter ego to another, from Dick's new identity as Nightwing, and in Jason's transformation into Red Hood acting as a culmination to his already violent leanings as Robin. Dick has been seen on Titans as a Detroit police detective, as a seasoned veteran version of Robin, and now settling into his new identity as Nightwing. Dick making an even bigger leap to take on his own mentor's crime-fighting alter ego wouldn't be that big of a stretch.
There's also precedent in comics of Dick becoming Batman for a time, specifically in the aftermath of Bruce Wayne's death in Final Crisis, with Dick guiding Bruce's son and the new Robin Damian Wayne as the new Batman for a time until Bruce's return from death. The Dark Knight Rises also concluded on a mantle passing ending, with Robin John Blake (an amalgam character of Robins like Dick and Tim) inheriting the Batcave from the retired and presumed dead Bruce. It wouldn't be that out of the ordinary for Dick to take the plunge from Nightwing to Batman himself on Titans. With the hints provided in season 3's trailer, Dick Grayson could end up donning the cowl to fulfill Bruce's wish that he become the Batman that he failed to be.