Soundwave on 15 January 2014
Financially though it makes sense too.
Nintendo badly needs something to sell an additional 10-15 million hardware units + software for them, and if the Wii U can't cut it, then something has give, this is a business, not a sentimental art class.
I think if a new Nintendo portable/tablet wasn't already fast tracked at Nintendo given the rising problem of iOS, it almost assuredly is now once Nintendo got a whiff of those underwhelming Wii U holiday sales in the West and the likely possibility that 3DS sales may have peaked already (look at Japan it's been down YoY for quite a while now).
If they have already chosen their SoC design, they can begin software development fairly quickly.
