I'd be in the camp that'd go with a much more sci-fi-slanted take on Batman - just to do something different with the film portion of the Batman franchise and not get pigeonholed into trying to carry on Someone Else's Vision. By that nature I'd probably also be in the minority that would have the guts to set it 25 to 30 years in the future. However, that does not equate to there being flying cars and robots and laser guns as far as the eye can see, either, and setting it in the future does not mean that I'd be interested in even attempting to adapt "The Dark Knight Returns" or "Batman Beyond" or "Kingdom Come" or any other Elseworldish take on the whole 'Bat to the Future' concept (pun totally intended) - maybe I'd crib elements out of them here and there, but for the most part I'd want this to be as much its own thing as TRKReturns and BBeyond and KC were. Although at least one ground rule would have to be set firmly in stone - any villain who's been used in the previous films, regardless of continuity, is off-limits, out of the picture, gone...meaning dead, in most cases: Joker, Penguin, Catwoman, Two-Face, Riddler, Mr. Freeze, Bane, Poison Ivy, Ra's Al Ghul, Scarecrow...all gone.
An opening text card a la "The Terminator" and "Blade Runner" would basically serve to get the GA up to speed as well as alert them right from the start that this Batman movie's going to be a little different: Gotham City, as well as much of the rest of the world, was leveled in an alien invasion 25 to 30 years earlier, and the world's greatest superheroes - including Batman - joined forces to repel the threat...which they did, but at an horrific cost. By the time the movie takes place, most capes are either dead, crippled, missing, or just plain don't have it in them anymore. Using technology cannibalized from the invaders, Gotham City was rebuilt as New Gotham, a towering Raygun-Gothic megapolis filled with the promise of a new era for Gotham citizenry (especially with Arkham Asylum and most of the Rogues in it obliterated in the attack)...but while you can change the skin, you can't change the animal, and within the space of two-and-a-half decades the grunge and dilapidation have taken over once more, the streets lit by broken neon lights and those aforementioned flying cars and robots and laser guns belonging largely to New Gotham's elite...and, by extension, the underworld. The end result is that New Gotham is a deadlier place than Gotham City was.
Enter into this world Thomas Wayne, New Gotham's champion boxer, raised on the streets by his trainer and father figure Ted Grant. Tom's known that the AWOL Bruce Wayne is his biological father, but he's learned to live with the shadow: he doesn't have the intellectualism or wealth that his Dad inherited (and enhanced considerably), nor is he aware at this point of his Dad's dual identity, but between the fame and fortune that comes with being a pro athlete, he hasn't done too shabbily for himself. So when Ted urges him to throw an upcoming title bout, Tom's not particularly keen to take that advice, and the resulting altercation between Tom, Ted and Tom's manager gets rambunctious enough to be of particular concern to Tom's new ultra-competent personal assistant, Cass Grayson, daughter of Tom's Dad's former ward --- little surprise should it be that Cass knows Tom's Dad's Big Secret before he does, and that Big Secret will come in handy when Tom's manager turns up dead and Ted in a coma following the bout which Tom refuses to toss. All the evidence points to Tom Wayne, and the ruined Batcave will have to serve as Tom and Cass's hideout as they try to puzzle out who framed him; what they uncover is that Ted might have wanted Tom to throw the fight in order to protect him from being the latest 'recruit' into what the pair discover to be a hideous brainwashing program. Furthermore, Wayne's current fugitive status is only serving to draw unwanted attention from the authorities, specifically Police Commissioner Barbara Gordon, who doesn't really believe that Wayne is guilty, necessarily - in fact, when she shows up alone in the Batcave, what's certain is her worst fears about the path Tom has chosen to go down to clear his name. Thus, with a third of New Gotham under mind-control hunting for him, it's a good thing Tom's old man left that unused prototype Batsuit and experimental flight-capable Batmobile in storage...
I'd say that in terms of the tone of this particular version of Batman, it's about Batman less as a force of fear and more as a force of sheer will, so there's room here for a little more humor, wry though it may be, than one would expect out of the character, especially given that it wouldn't be Bruce Wayne behind the mask this time - one of the recurring points of the story is that Tom is NOT his dad, and therefore doesn't cut quite the grim figure Bruce did; he's rough enough around the edges that he has more in common with Harrison Ford in his prime than he does with Christian Bale or even Michael Keaton.