Nikon says they will not make bigger sensor mirrorless cameras.
If you were hoping to get an APS-C or even FF mirrorless camera from Nikon you will have to digest that. In an interview at Dpreview Nikon said:
We still believe that Nikon 1 has room for further evolution. This is the area we want to put effort in to, rather than making bigger sensor mirrorless cameras.
We have two different categories: the D-line and the 1-series, and with these lineups, we believe we’ll meet all the needs of customers.