Dave Filoni said:
"We will see many things that are famous to Star Wars, but have not appeared on screen in a while. Star Destroyers, TIE Fighters, and Stormtroopers – basically the Empire is back and that is a big change, since, for many years, we have only seen the Republic in action. The tone of the series is also different. The Clone Wars got very dark as we headed towards the end of the war and the downfall of the Jedi. Star Wars Rebels brings back the banter and faster pace that the original films were famous for."
I think is is an awesome quote right here.
I'm not going to go so far as to think they'll ignore the prequels totally, or try to erase them or whatever, but since 1999, we've been totally inundated with the PT. Toys, games, shows, movies, nearly everything Star Wars since TPM has been PT related, and at this point, the OT is kind of a blip in the past. Sad as it is, with all the PT stuff, the OT has become more or less irrelevant in terms of Star Wars, especially for new Star Wars fans, who may never have seen them.
I fully admit I'm fanboying here about Filoni and stuff, but this is really what the OT needs, a shot in the arm to get new fans interested in it, I mean, sure we all got hooked on the OT, but times have changed, and rather than moping about it, it's nice to see some action being taken to bring the OT back to the forefront, to make it relevant again. It's been so long since we had any real OT material (aside from books, but those really are meant for established fans who don't need help visualising stuff), and I think that Rebels can provide that intro to the OT for the kids who may be more easily enticed by the flash and dazzle of the PT compared to the slower, less intense (but far superior) OT.
It's certainly better than rebooting the OT, or trying to "update" it a la 1997.