So pretty much the big "epic" Mario Galaxy that everyone was hoping for will start development as this 3D Land sequel wraps up.
There's basically now 3 Mario platforming series'
2D Mario - Current the "New" series.
3D World/Land - A 3D Mario, that takes a lot of design cues from the 2D games.
3D Galaxy - The spiritual successor to the legacy of Mario 64/Sunshine, true 3D Marios.