Nintendo has recently released a new video for that shows off a new Excitebike-themed arena for Mario Kart 8 that will be included in the first DLC pack. If you remember the classic NES game Excitebike, then you can pretty much see where this is going as the course is basically a giant Excitebike track. However, watching the video it seems that the track can actually take on different designs as it shows the same section of the track, but with different designs. That would actually be interesting as you wouldn't know what version of the track you're playing until you come across the obstacles.
Also, I hope the course music is the music featured in the trailer. I'm starting to get hooked on that remix of the Excitebike theme.