So last week Studio Mir, the studio that animates Korra, released this image: http://25.media.tumblr.com/tumblr_m6b56qFI9t1qdbhwwo2_500.jpg
I can only speculate, but the image probably hints at part of the story plot for the next season. If you look at the image, Korra and Asami are both standing in front of a temple looking building that looks like it could be situated somewhere in the Earth Kingdom or Fire Nation. I think this could mean that the next season will have a bit more of a traveling element to it like in ATLA. Personally I was disappointed with the lack of exploration that Korra had. They could've at least went into one of the skyscrapers! Well that's my opinion what do yall think?