I'm 50/50 on the belief of whether there's room for a 3rd somewhat-similar console box on the market. On the one hand, different-for-the-sake-of-different has bitten Nintendo in the ass more than it has helped them over the years, and at the end of the day their best software ends up being the games that are the most "traditional" (Smash Bros, Mario 3D World, Tropical Freeze, Mario Kart 8, all playable with the traditional Pro Controller and essentially built with that paradigm from ground up). The WiiU's first party library is nothing short of amazing and there's no doubt in my mind that the failed platform that is the WiiU held back the popularity of its software. Smash 4 deserved better sales than Brawl, Mario Kart 8 deserved more sales than MKWii, etc. Making consoles this way is also incredibly risky. If their gimmick doesn't pan out, they're out for the next 4/5 years and they have to write off that entire generation. I doubt Nintendo enjoys being in the position of their market potentially crumbling each and every time they're due for a new console.
On the other hand, great software doesn't necessarily translate to good sales or solid 3rd party support. Not because I believe that 3rd parties "have it out" for Nintendo, but because it doesn't make financial sense to shove in more target platforms if the money isn't there. Then there's the question of who such a console would be for. Would Nintendo really be that successful in pulling PS4/XB1 consumers away from those platforms and into theirs in significant enough numbers? Can Nintendo even provide a comparable experience? I'm specifically talking about the online infrastructure. I know Nintendo has made some pretty significant leaps in regards to how it handles anything and everything online, but I'd still say it's far from being on par with Sony's and MS's competing services. It's not super important now but if they were to go after Sony and MS's lunch this becomes a factor. It also doesn't help that Nintendo hasn't tried to court this audience since the GameCube days. At this point the effort in going up against MS and Sony directly would be akin to entering a new market.
So I can't really see Nintendo continuing to exist in either of these spaces comfortably. Sure, Nintendo doesn't need to be as much of a juggernaut as Sony/MS, but I doubt Nintendo or their investors would be particularly happy with taking up the mantle of the "niche console manufacturer". It's pretty clear they DON'T want to continue putting out consoles that sell 13 million worldwide. I don't think their infrastructure of being a software developer, publisher, hardware manufacturer, and distributor can sustain sales like that for an extended period of time. But at the same time, I don't know that Nintendo has the ability or resources to try to re-enter the console market with a traditional box and competitive specs and succeed in that space. And I highly doubt that going 3rd party would solve any of their problems.
If anything I'd wager their best course of action is whatever nets them the sweet spot between hardware uniqueness and 3rd party support. While 3rd party support is not sufficient to have comfortable success, I do have to say it's necessary. I don't think anyone can look at what happened with 3rd parties and the WiiU and say to themselves "yep, this went a-OK".
