Nintendo has just teased a NX reveal which is scheduled for the 21st of October 1 am AEST:
Be among the first to discover #NX. Watch the Preview Trailer at 7am PT/10am ET
— Nintendo of America (@NintendoAmerica) October 20, 2016
Trailer will be 3 minutes long according to this translation:
[Notice] exposes Nintendo home video today from 10/20 23:00 totally new concept gaming NX (development code name). See is a short 3 minutes or so, but if you don’t mind.