So, just checked out the first episode of this show and it was great!
Reading some plot synopsis online made me think, for some reason, that this show was gonna try to be much more gritty and dark (Metal bending, revolutionaries, cars etc.) than Avatar was, but it seriously isn't. It's just as much fun as Avatar was and that's really cool. Like it was said before, Katara is still around and we even meet Toph's daughter who's in charge of the Republic City police (Though kind of a jerk) so Toph might still be alive too. Heck, maybe even Zuko's alive, who knows.
It's a pretty fast episode, but it works well: It shows that Element-Bending, while still powerful, is pretty outdated, that technology became really big and that people don't really need much of the Avatar anymore (Though she is welcomed to Republic City with thunderous praise) So it's certainly a great start and I really hope this kicks into another four seasons series.
You know what else is awesome? Steve Blum voicing Amon, the apparent leader of the Revolutionnaries and most likely the main antagonist of the show. You might know Steve Blum as Orochimaru from Naruto, Spike Spiegel from Cowboy Bebop or, for a completely different kind of performance that really shows his range, Guilmon from Digimon Tamers... Yeah, Orochimaru and Guilmon have the same voice actor... Kinda shocking.
Anyway, totally hyped, now!