At the time I'm posting this, there is only a Japanese trailer so the English names of the newly revealed battle courses are unknown. Besides the four already revealed before, there are a total of eight battle courses. There's a Wuhu Island battle course (it may be the same battle course from Mario Kart 7) as well as a Dragon Driftway-like course, an outer space-like course, and one that seems to be inspired by Sweet Sweet Canyon. It has a castle in it and it has the Peach & Daisy Royal Patisserie logo on it. There is a Sweet Sweet Canyon remix that plays at the end for the amiibo part, which could be the theme for that battle course. Maybe it's a new Peach/Daisy battle course?
Also Gold Metal Mario, please tell me that's a costume for Metal Mario like Gold Mario is in Mario Kart Arcade GP DX.
Edit: Wuhu Town from Mario Kart 7 is returning and Sweet Sweet Kingdom is the name of that Sweet Sweet Canyon-like battle course.