I don't think those are still from the movie itself. I'd be very surprised if we'll see any of the finished CGI work before the first trailer releases. These were labelled as "concept art" by Avatar's social media pages, but looking back at the concept art for the first film, the imagery was pretty spot on in regards to the final look and feel.
I would really like to see Cameron knock the 4 sequels out of the park. He's said in interviews that the first film will basically act as the prologue, setting up the world, its people, and a bit of a backstory as to why the humans are there in the first place. The real meat, or the main story if you will, is what the sequels will be tackling. I have no idea what to expect. It's confirmed that Jake and Neytiri will have children in the sequels, which confirms a good time jump. I assume this also means that the humans have also regrouped and will play a large role again as well.
I still stand by my prediction that the humans never left Pandora and simply relocated to another base or settlement somewhere else on the moon. There could be several for all we know.
One thing I'm really hoping for is that each movie tackles different regions/environments on the moon. The first movie focused on the forest, and the second one is confirmed to primarily revolve around clans of the sea. It'd be cool to explore all of what Pandora has to offer. The first movie revealed the existence of clans on the cliff sides and plains as well.