BronyGalore from the MLP Trading Post has found some interesting ponies on Taobao that could be prototypes of new lines.
There's a bright, translucent Pinkie Pie with multicoloured hair. She kinda looks a bit like the Wave 8 blind bag ponies. There are currently no translucent ponies in G4 availiable (other than blind bags) so she could be part of a new line. However, Hasbro has done some glittery translucent ponies in the regular size before that haven't been released so I'm remaining neutral on this one's status until we find if it hits shelves or not.
There's a bunch more of interesting ponies under the break!