Even assuming Nintendo suffers more market contraction next cycle, which is highly possible, all the more reason to have a unified platform in that case so you don't get stuck with things like the next Zelda and Splatoon 2 and Mario Kart 9 or 10 selling to only a small chunk of your actual hardware base.
Lets say their portable line continues to suffer a bit at the handhelds of mobile/tablet and contracts to say 50 million down from about 68-70 million this cycle, then the console more or less is the same 15 million or so, that's still 65 million hardware units ... enough that you would want all your games to be available to all your buyers. Segregating software is just costing Nintendo money at this stage since they don't make much/any profit from hardware to begin with.
Having to pay $500 just to play all the Nintendo games is a losing proposition too, even most Nintendo fans choose not to do that (those who own both the 3DS and Wii U are the small minority). The only thing a segregated library is good for at this point is keeping games like Mario Kart 8 and Splatoon and Bayonetta 2 locked off from selling to the 80% majority of the Nintendo user base. A game like DKC: Tropical Freeze is such a shame ... could have sold 2x-3x more easily I think, it just happened to be stuck on the Wii U and that's rough.
