My guess is
Fusion is a 20nm system-on-chip mobile part with a ARM v8 core + customized AMD mobile GPU that shares some dev libraries/architecture similarities to the Wii U GPU, allowing for easier porting of Wii U engines/games.
Apr-May (Golden Week) launch in Japan with say Animal Crossing. Super Mario Galaxy 3 for late summer, this time Nintendo will make sure they have a big post-launch title to avoid a drought period.
June 2016 launch for North America, July launch for Europe.
November 2016 is the launch of the Home Fusion variant (basically the console version).
New 3DS will be kept around as a budget option ($99.99 for the small version, $139.99 for the XL) for a few years afterwards.
Holiday 2016 for Japan -- Dragon Quest XI goes multiplatform ... PS3/PS4 or Fusion (home or portable). Fusion version sells the best.
