Currently Online 
From NeoGaf
Apple TV estimated shipments - ZhugeEX
2007- 0.3 million
2008- 0.3 million
2009- 0.7 million
2010- 1.6 million (REV2)
2011- 2.8 million
2012- 6.5 million (REV3)
2013- 7.0 million
2014- 6.0 million
This is the old Apple TV model, but you can see from 2012 onwards it's far outselling the Wii U and selling about on par with the XBox One. If the new model revision causes a fairly decent bump, it could challenge the XBox One for the no.2 spot at least for most hardware moved this generation.
NX I really don't know about, it could bomb just like the Wii U did, Nintendo has a (terrible) habit of fixing some old mistakes only to then make completely new ones or to take years in fixing a mistake to the point where it doesn't matter any longer.
Sony is going to cruise to no.1 though, I don't think there's much doubt about that.
