In 2014, Iwata said he expected them to return to "Nintendo-like profits" in the fiscal year ending March 2017. That makes me think a 2016 release was always planned.
https://www.nintendo.co.jp/ir/en/library/events/150217qa/02.html
That was actually 2015, after the launch of amiibo and the failures of both the Wii U and 3DS.
How do you know? We don't even know what the handheld will look like.
Touch screen, I mean without it, they don't have the same inputs at all. Mobile software would never work either and that has it's own problems if they ever wanted to port anything.