If Gotham City and Central City had a contest about which place has worse crime, nobody would want to judge it. But at least The Flash's home has a squad of brainiacs and super-powered folks aiding the local P.D., while Gotham only has/had Bruce Wayne's proto-Batman temporarily stalking criminals. Though Bruce is currently living it up as a non-crimestopping schmuck, actor David Mazouz has a pretty good (if almost entirely non-feasible) idea for how a crossover with The CW's Flash could help things out.
The Flash kind of had their run-in with Flashpoint a couple of seasons ago. Maybe there could be another kind of Flashpoint where Flash runs back in time and goes to Gotham and maybe tries to stop Bruce Wayne's parents' murder from happening. Maybe not the traditional 'Bruce Wayne gets murdered instead, and Thomas becomes Batman thing,' but something along those lines where the whole world gets whack and it's up to Flash to fix things in Gotham.
Let's push aside all of the understanding that Gotham and The Flash would have to jump through some major hoops in order to make a crossover happen -- although that Fox and Disney deal is a similar kind of unprecedented scenario that helps crossovers happen -- and let's just focus on why David Mazouz's idea is cool. In the first place, the Gotham star was quick to say to ComicBook.com that the crossover would need to happen on the Fox series, which would presumably mean that any timeline hiccups caused by Barry's time-travel shenanigans would be tethered to Gotham and wouldn't carry over into the Arrow-verse. That distinction, I believe we all know, is the main reason why Barry should ever be able to use time travel again, since it never, ever, ever goes well.
Giving Gotham a "Flashpoint" episode would also be interesting because...well...it would be Gotham's version of a "Flashpoint" episode, and there are few things in life more deliciously intriguing than "Gotham's version of __." The show often takes on well-known DC comic characters and situations, but it almost always adds a ridiculously enjoyable spin to them that Gotham has totally earned over the years. With the Thomas Wayne-as-Batman angle theoretically not on the table, there are plenty of bizarre ways for the Waynes' short-term survival to affect Gotham City.
If Thomas Wayne had lived, then his involvement with the Indian Hill facility (as well as the Court of Owls) would likely have broadened, which would be an interesting avenue for the show to go down. Similarly, Bruce wouldn't have gotten involved with Oswald, Jim or almost any of the others that he's bonded and battled with, so one wonders if he would even be interesting enough for viewers to follow. And how would it all play into Penguin's rise, Fish Mooney's fall and how the Falcone family's lives panned out?
Aside from the plot, even, it would just be fun to see Barry Allen drop a little sunshine into Gotham City, where the sun only shines when it's mean to give someone a headache. I'd love to know what Barry would think about all of Gotham's rogues, particularly Hugo Strange's monsters. But of all those sour-minded characters, I think Victor Zsasz would be the most fun to watch, since he would fit right at home in the Arrow-verse. (Incidentally, I bet Alfred and Joe would have a whale of a time together.)
So while we probably won't ever get to watch any Gotham and Flash crossovers coming around, Flashpoint-related or not, we can expect to find both shows returning to their respective time slots in 2018. Gotham returns to Fox at some point early on, while The Flash will bring its trial-based comic story to The CW on Tuesday, January 16, at 8:00 p.m. ET. To see what other new and returning shows are coming to the small screen soon, head to our midseason premiere schedule.