According to the latest datamined SWTOR info, we’re heading to Chiss space! In a future patch we’re apparently going to Thrawn’s adoptive family’s planet:
Copero was a planet of the Chiss Ascendancy in the Unknown Regions and was located in the Copero system. It was home of the Mitth family, one of the Chiss Ruling Families, and thus was located on the Path of the Houses, a hyperlane that ran through the Ascendancy’s core territory, along with the homeworlds of many other Ruling Families. Copero was also the location of the Chiss Ascendancy’s largest shipyard.