Well, how do you define success? If you isolate Microsoft and Sony console and console entertainment development divisions, Nintendo is clearly successful. They're a fiscally conservative company that has enough revenue and capital streams, and the lowest debt-to-capital ratings amongst them. So much so they can afford to fund making consoles like the WiiU until 2050. Nintendo never release products without surety against loss within the first 6 months. Unlike Sony who will borrow vast amountsof money,and take multiple pledges toother subsidiary firmsand interests to get aconsole to market. Such as the PS4 ... ditto Microsoft, who has been underperforming massively compared to Nintendo and Sony.
In terms of real risk, if you isolated Sony Computer Entainment and Microsoft X-Box divisions ... Nintendo has a better chance of both short term and long term gains by just looking at economic performance.
As much crap as people want to put on Nintendo, they do have a habit of at worst breaking even, and at best taking the world by storm. Compare that to disastrously expensive failures such as XB1, Kinect, and the Vita.
Nintendo will make a profit out of the Switch by the first quarter of next year. Compare that to XB1 which Microsoft believed they couldship 200 million units in a year (try atenth of thatby the first quarter of this year). Which company is drinking the Kool-Aid and which one is being cautious? Certainly Nintendo have a habit of being overly cautious, but they don't seem to have directors doing as many lines of blow when it comes to realistically judging market demand.
I forgive Nintendo (as a corporation) ... they can't plan for 200 million units and sell only a tenth and still expect to remain solvent. They're a smaller company and so their risk is massive. Their cautiousness may be overly indulged ... but it's doing them credit far more often than not. Not only that, but their cautiousness does not extenbd to the creativity of designing their consoles. Say what you like, Nintendo products offer something that youcan't get on a PC. Their creativity and ingenuity in tapping unexplored ideas of gameplay have more often than not brought them success and given them an indulgent platform that they are, of all the console makers, the only real innovators.
Bridling economic conservatism with a pursuit to provide a new experience of gameplay is, ultimately, something in their favour.
While I have severe scepticism that consoles will ever be as they were in the 80s and early 90s, I do think that Nintendo is in that best place to become as if the 'Apple Upset' breakout mold for console makers. If any console maker can do it, Nintendo will be the one. I doubt it ... but that is more indicative of the entire aspect of console gaming as a whole.
If Nintendo could create a Wii-level popular unit every 4.5 years, then yeah. Sky's the limit. Moreover I doubt wholeheartedly that Sony or Microsoft could ever capture that 'Wii Moment' of console profit glory. I honestly don't see Sony or Microsoft innovating enough to capture that sublime co-ordination of marketing, accessibility and near iconographic substance the Wii achieved. People didn't gel with the idea of the Wii, too. That isnot to say the Switch will achievesimilar numbers ... but by the same token, that's not to say that Nintendo as a whole can't ever replicate that success again.