Oh I totally get what you're saying, and I remember them saying it myself, but if I were to break that down, it sounds like a strategy specifically designed to bring in what I would tentatively call casuals.
Now not to say that is wrong, as a good percentage of PS4 owners are funny enough casuals! But they also have a very strong core audience as well. And one of the biggest draws for the core audience are games pacifically aimed at them, and what Nintendo has shown so far with this app, may not appeal to that type of gamer. And by extension there efforts to allure these customers would be wasted to a certain degree. Which would then require them to rely On the tried and tested method of drawing the core gamer audience, big AAA console titles. Best way I can see them achieving this is if they're able to use a relatively stable and to a certain extent disposable line of income, for the purposes of internal development and "financially helping third parties out", if you know what I'm saying.
As I believe the core of a consul business is in fact the core gamer, now Nintendo most likely will secure their own core audience, and will most definitely bring in the "casuals", but for them to be successful they need to targets these console agnostics, that they seem to have had issues gaining as an audience for the last several generations, you know the type, the ones who support the third parties. That's why I believe it would make sense for them to reinvest any financial gains from the mobile market back into their core consul business.
That's why I say I'm interested with what they going to do with the money, if they generate any from there mobile apps.