Gotham star David Mazouz thinks Batman is definitely on his way to the series. The prequel show has mainly been about creating the world the hero will eventually inhabit in preparation for the introduction of Batman. And after a key scene at the end of season 3, we began to see Bruce Wayne embrace a vigilante persona. He hadn't donned the cape and cowl, but he wasn't far off either. Season 4 is looking to continue that story, as Bruce develops a separate identity for his nighttime activities.
It sounds like across season 4 fans may begin to see a form of proto-Batman. Maybe not quite to a 'Year One' standard, but a beginning in the character's crime-fighting career. Mazouz, who portrays Bruce on the show, has clearly been looking forward to the Batman storyline coming into play for some time and expressed that his identity would become a huge component of season 4.
When speaking to Comicbook, Mazouz also discussed the idea that there are other things that go with having a vigilante persona:
"Bruce really is taking on this vigilante persona and all the things that go along with that. Whether it be creating another persona, a public persona, that’s also definitely going to be a major part of Bruce’s journey this year. His relationship as this other person. Batman is coming. Absolutely."
The writers behind the show have previously said that the series would end with Bruce finally donning the outfit, so it doesn't seem as if Gotham is quite there yet. However, they're definitely looking to push Bruce in his journey to becoming the Caped Crusader. Mazouz also went on to mention that he was initially worried that the Batman storyline would stagnate a little if the writers began to hold back the vigilantism.
"Another thing I was worried about was we were going to get to Season 4 and the writers were going to go, 'You know, I think we took it a little too far too fast. Let’s backtrack.' And the exact opposite happened. The trajectory is just continuing in that direction. I would say, I would know it’s accelerating in that direction. It’s not going to stop."
From his comments, it looks like season 4 might be more heavy handed with Batman than was initially thought. While there's no word on whether season 5 is on the table, it's entirely possible that the showrunners have discussed the idea of Batman appearing on the show a little sooner than expected. And since there are rumors swirling about the Joker being properly unveiled before the show's end, that might be a showdown to keep your eye on.