The finale was completely stunning. The best I have ever seen from American television animation personally. Zuko's mom and Azula were such cliffhangers though....bah! And we get the kiss! So long Boomie and Space Sword.
All Hail the Melon Lord!
All wrapped up pretty neatly overall though, it wasn't as rushed/contrived as I feared it might end up.
I think what the creators mean is that future stories in the Avatar universe won't revolve around the current main cast anymore. This story was told and they'll move onto new ones, but that doesn't mean they won't use any of our favorites....it'd be a real shame if they chose not to honestly.
I think with the writing they've done so far they could easily include any of Team Avatar into a future series/movie without making them the focus.