I’ll admit I’m a pretty extreme case! But still, light brown just ain’t blond.
I just clicked through a bunch of val kilmer images on google search, and two conclusions come up: His hair has been wildly different in color at different times, and I could maybe roll with the “dirty blond” label at some points, but never fully blond, and still usually brunette. Conclusion 2: Holy Hell Val Kilmer has been looking rough over the last several years.
As for Gyllenhaal, I don’t really see it, but I’m a fan of the actor, and if the casting director is convinced I’ll be along for the ride. They’d have to do more work artificially creating a Batman voice for him and his pipsqueak voice over any other actor yet, though! Personally I think he would be a better fit for some of the classic villains, especially Joker/the Riddler.