A recently leaked video shows what appears to be an unfinished line test from a scene in the upcoming series (screenshot located directly to the right of this section). In this 9-second clip, we see what looks to be Korra fighting two opponents without the use of bending. Actually, she demonstrates various forms and fighting styles that resemble techniques from several bending arts.
In the first panel, Korra is setting up a move that was used several times in Waterbending, specifically a form that involves the turning of an opponent's force against them. Korra uses this form to block herself from her first opponent's attacks, then uses it to destabilize him, allowing her to effectively overwhelm him with a series of jabs and punches aimed at the chest and head. She then transitions into a rooted stance seen in the second panel to finish him off, which is quite similar to the stances used by Earthbenders prior to and during the performance of a move. A second opponent charges immediately following the first opponent's defeat, and Korra continues to use earth-based forms to counter his attacks. We see in the third panel that Korra directs an upward kick towards her opponent's face in order to stun him. This kick is the same move used by Earthbenders to lift boulders, as well as the same form used by Firebenders to create blazing rings and arcs of fire. Another Firebending-inspired move is seen in the fourth panel, where we see Korra utilizing a move similar to the one Zuko used to throw Azula off her balance during their Agni Kai.
This clip has not been confirmed to be legitimate, although the fact that it originated in Korean studios and that it bears striking similarities to the concept designs used in the first series suggests that this is a reliable clip