While on the topic of GDC, I can mention again that Nintendo's presence at GDC 2016 is miniscule:
Source:
http://fp37.a2zinc.net/Clients/fpUBM/GDC2016/public/eventmap.aspx?shExhList=1&Shmode=E&MapID=25
They only have these three small "booths" in the business center. I haven't been able to find any images of what this space looked like at GDC 2015.
In terms of sessions, Nintendo hasn't got any speakers (Steve Rabin will be there of course, as every year). Closest is
Catch 'Em All: Pokemon GO and Real World Gaming by Niantic.
They can of course demonstrate NX behind locked doors, but in terms of public information regarding NX at GDC 2016, things aren't looking too interesting.