I am going to say it one more time for the people in the back: we want Batman to enter the Arrow-verse! It's something that's been demanded by fans for years, and it seems like the next logical step now that we have a small screen Superman. Of course, it's no secret that logistics in this DC TV universe have prevented such an encounter from taking place, but Gotham star David Mazouz seems to think that the Arrow-verse's smart use of time travel could now make it easy for Central City characters to meet the citizens of Gotham City. The actor explained:
So we already had fans who want to see this happen, and now Bruce Wayne himself intends to see an Arrow-verse crossover at some point as well. This doesn't inherently guarantee a crossover, since finances and rights issues are a thing, but it goes a long way towards making a case for it. The folks at DC would simply need to craft a story in which Barry Allen or The Legends use their time travel abilities to go back to the non-specific era in which this particular version of Gotham City exists. From there, they can encounter Bruce Wayne and get into all sorts of wacky escapades. It's a phenomenal idea, although after Flashpoint I'm sure most people would likely want to kill Barry if he ever tried another time travel adventure.
It seems fairly obvious that the Arrow-verse has (intentionally or not) been building towards the eventual inclusion of Batman in some form or another, whether it's Gotham's take or someone else. Arrow has featured references to Oracle, NIghtwing's home turf in Bludhaven, and several iconic Batman rogues -- notably Harley Quinn. Beyond that, The Flash already confirmed that Wayne Industries exists in the Arrow-verse. With so many key pieces in place, there's no reason not to press forward with this idea...from a fan perspective.
Perhaps the most interesting aspect of David Mazouz's comments to Moviepilot about a potential Arrow-verse crossover with Gotham (during the recent Heroes & Villains Fest) is the fact that he says nothing about the multi-verse in his answer. We have operated under the assumption that FOX's version of Gotham City exists in an entirely different version of Earth than any of the Arrow-verse shows, but it seems that it may just exist in the past, which we'll go ahead and believe until Greg Berlanti & Friends say otherwise.
If that's the case, and DC ultimately decides to make Gotham City a part of The CW's Earth-1, then all of the essential pieces are already in place to make this happen. And even though Bruce isn't Batman yet, Flash could just not travel back as far as we are in the show now, so that he'd arrive after the Bat-transition already happened.
Gotham airs Monday nights at 8 p.m. EST on FOX, and the Arrow-verse shows will return to The CW this fall. If you're on the lookout for more up to date information on the rest of the highly anticipated series that will debut over the course of the next few months, take a look at our summer TV premiere guide.