So I've often thought about this and I know they like to keep Batman in the movies but wouldn't a good way around that be to do an else world series about Batman? I mean I'd give something like that a shot especially if they did a Gotham by Gaslight or Batman Vampire or some weirdo combination of the two type story. I think it would really depend but I'd totally watch a series about Batman even if it was else world based so long as the writing was good.
Ultimately I'd rather Gotham By Gaslight be made into a series because I think it'd be more interesting to see his enemies adapted into a different time period. Though I think it'd be cool to get a series comic or tv that takes a Gaslight setting and combines it with a supernatural element/spin on the Batman rogues.