CAVEAT: I am neither up-to-date with Arrow/Flash (up to Episode ~15 in season 3/1), nor have I ever watched Gotham, Supergirl, or any other recent-ish DC Live Action TV show.
Please don't spoil me, but there are some minor spoilers here...
I have a theory (and it's not bunnies or midgets).
This might not even be an original theory, since we aren't all caught up, but this is my blog :P
Ever since we started watching Arrow, the comparisons to Batman could not be missed, with even just the basic premise: a rich socialite experiences traumatic events in his life and becomes a masked vigilante.
But specific elements of the greater Batman story do appear throughout the show as well:
The Suicide Squad.
Harley Quinn locked up in an Argus facility.
Constant references to Blüdhaven, home of Nightwing.
Ra's al Ghul and the League of Assassins.
In Flash, there's even a headline in the "future newspaper" related to Wayne Tech.
Even these few details point strongly to Batman's existence in the same universe.
But where is he?
Why aren't Oliver Queen and Bruce Wayne old party buddies or business partners?
Why not even the faintest mention of Gotham City?
Now, you could say "because DC/WB lawyers, movies, contracts, yada yada".
But I don't
(want to) think so.
At the same time, there is this show Gotham.
(again, I haven't watched it)
A young Bruce Wayne loses his parents and sits idly watching the criminal goings-on in Gotham City. He isn't Batman yet, and might never become the Dark Knight in the continuity of this show.
But what if...
What if...
What if Oliver Queen *does* show up in Gotham City some time in the future?
What if Oliver Queen meets young Bruce Wayne, much like he found Roy, and decides to train him?
What if The Arrow and STAR Labs help to create the Batman?
(What if Cisco names him?)
What if this is all an elaborate secret buildup to a new Batman show "done right"?
Alright, I've gotten that off my chest.
Go ahead and tell me that something I'll see in the future leads to a contradiction of my idea.