The pushevs article about a 40 kWh battery is from last July. Nissan obviously didn't switch to 30/40 kWh batteries for the 2017 MY, so I certainly wouldn't call it "news". More like a good guess gone wrong.
30 will become standard and 40 will be optional I bet. Renault released the Zoe this year with 41kwh on board. Renault, Nissan, and Mitsubishi have been partnering on EV tech for awhile now.