They may just be silhouettes, but it is clear to make out who these characters are. Book 1 Water Katara, Sokka, Aang and Zuko, Book 2 Earth Toph. Then on the Korra side of things we have Book 1 Air Mako, Korra and Bolin.
Given that Lin is the first figure they have revealed and she is not shown here, it very much suggests that they are releasing some form of Avatar figure line.
The big question is if they will all be the same style of figure as the Lin they have shown off. That is an 11 inch hand painted pvc kit. That is a fairly big figure and pvc figures are usually pretty expensive, so I am not sure if they would go as far as to announce a full line of 8 (possibly more) figures which are all big and expensive. These may end up being smaller figurines that will be more affordable.
Right now all we really know is that this seems to be a new company that has got the Avatar licence to produce figures and they will have a regular and a special SDCC version of their Lin Beifong figures, you can see more about those 2 figures here and here.
This is pretty big news as many fans have wanted a physical representation of their favourite characters for so long and now we are potentially getting just what we want. I assume Zwyer will reveal more at SDCC.