I'm cautiously optimistic (they've got the "A History of Violence Dude," so it's off to a good start), but it's going to be hell casting Nina and Johan, seeing as it's really plot important that they're Half Identical Twins (warning: TvTropes link).
Also, they'll probably make Tenma white (and, considering that it'll probably come out within a couple of years of the Astro Boy movie, change his name), because Hollywood's always dumb and obnoxious like that