Going mobile could be a fine additional stream for Nintendo content. I've been playing a little Pokey-Mans Shuffle on the 3DS and wishing it were available as an Android App. I'd like it better. I could see a Mario endless jump-runner as a fun time-waster. These don't threaten me in the least. I'll buy them. And I will continue to buy Nintendo consoles and dedicated handhelds (or hybrid systems if that comes along which seems likely from the NX announcement). There's room in my life for all this stuff. It's fine and if it makes Nintendo gobs of money, great.
I could even see some of the more "mainline" games having a perfectly serviceable mobile version. I think the Mario RPGs (Paper Mario, Mario and Luigi or just a new Super Mario RPG) would work just fine on mobile. I can see their button-press to enhance combat or defence during battles working perfectly well as a tap on a mobile device touch-screen, especially as those screens are typically more tap-receptive than DS or WiiU touchscreens. Now, if I could get a meaty Mario RPG and pay a bit extra so it becomes cross-buy on my devices of choice, and I can continue to play the same save file across all those devices? That's Gold, Jerry. Gold.
Or if I could get a Smash Trophy Bank app on mobile, where I can look at and read about all my Smash Bros. Trophies while waiting in line, instead of having to boot up the game for that? I'd love that. When I boot up the game, it's usually because I want to play it, not read about trophies. But I still want to do that eventually.
The upcoming Mario Puzzles and Dragons thing should go mobile. I would like that.
How about a Missile Command clone where the waves of descending missiles are Metroids and it has background music from the series? Again, as a fun time-waster, I'd definitely buy.
There's a ton of ideas that would work well for mobile. And, as it is Nintendo, I'm sure they'll put the strangest, quirkiest twists on the products that we never saw coming but which will be utterly charming. Count me in.
Now, I am sure you are going to make the argument that developing for mobile would eat up development band-width that could/should be dedicated to "real" game development for Nintendo-dedicated gaming hardware. Well, I just don't buy it. Sorry. I don't have anything concrete with which to argue the point other than the fact that Nintendo doesn't usually steal developer time from dedicated games to do side projects. They partner up or they outsource. Or they re-position teams to do new stuff after they've finished with a particular project because they need to keep them working anyway and the type of just-finished project doesn't need or warrant an additional installment right away.