I don't understand why everyone thinks Nintendo's quality would drop if they went multi-platform. If anything, Nintendo's simple aesthetics would be easy as pie to quality control.
People keep using Sega as an example, while ignoring companies like Cryteck, id, valve, and many other companies that put products on all systems that have non existent technical issues, while trying to push a lot more.
Nintendo would be just fine in the quality department.
It leaves the impression that Nintendo fans believe they're the only company in the industry that's capable of putting out a quality product, and if they lost hardware, that would somehow stop being true.
Well, first off, I think your examples are poor choices, weird ones too. None of those companies have the sheer output of titles that Nintendo does, so having to do a few more platforms for your triennial game release is probably a pretty good deal, maybe necessary even. Nintendo however puts out more in a year than your three examples combined have in three years so you can imagine how the effort between the two would be massively different as well as the ramifications to Nintendo's release schedule.
Anyways though there's no reason that going third party has to result in crappier games but it has a good chance of happening because of people shit. Take Xenoblade Chronicles X, this game is likely expensive as hell to make and isn't going to sell shit, well not enough to be make up it's money probably, so why is it getting made? To check a box, the JRPG box. Why make something to check a box? To sell a system, the Wii U. Why make something that may well lose money just to sell a Wii U? So that that gamer who really wants Xenoblade Chronicles X may now buy something else on the Wii U. I likely would not have bought a Wii U if not for knowing we'd get X and a new Zelda. Period. But because of just two games, one of which is probably niche as hell I bought their stupid box and since it was waiting around doing nothing for months I bought some other shit for it because why not? Now I have Super Mario 3D World, Smash Brothers and Mario Kart as well, but I'm not lying when I say I would not have bought a Wii U for those titles. Supporting a console's a very involved endeavor especially when you have as limited third party support as Nintendo does and it's actually a different concept than just selling games as a third party. Because Nintendo is trying to sell you a box, whether that be the Wii U or 3DS it doesn't matter, they make games for them and since they're trying to appeal to as many people as possible they branch out and make all kinds of different games and experiences. The riskier bets are tempered by the idea that even if it loses money or just breaks even it's still adding to the overall ecosystem of that platform which in turn may help sell another box, another game or both. That means that sales numbers are rather dubious when discussing first party titles because games sell other games, as I said earlier X probably isn't going to sell gangbusters but because of X I bought SM3DW, MK8 and SSB, 3 titles that were going to sell anyway but not to me if I didn't buy the box for something else, so these odd unpopular games are more important than their cold hard sales data will ever show. Now take away the need to sell someone the console, become just another third party developer, and what incentive beyond just some noble desire to let your directors experiment is there to make a game that isn't going to sell gangbusters?
Don't get me wrong, Nintendo would still try at first because they wouldn't know any other way and at first so they'd try and keep things running as usual, stuff already in motion would just get ported over and they'd keep all their teams busy and start new projects but once the argument can no longer be made that a niche game is helping to sell your own hardware or another one of your games how can they justify to their shareholders making games that don't see well or outright lose money? The answer is they couldn't.
Now I honestly don't quite get why Sega's fallen as hard as they have in all honesty, their initial post Dreamcast stuff was actually pretty good and I never really followed how well or poorly they sold or whether they're just super poorly managed or what. I don't think it's fair to say that Nintendo would fall as hard as Sega even though it's impossible to point to a single company that had a console, went third party and then thrived. There's clearly multiple things at play in such examples, usually the company was of course making bad decisions as a console maker that led them to such a financial state that they had to exit so of course it'd be somewhat foolish to expect that all of a sudden without the hardware side of their business that then all of a sudden they'd get their act together, no, it actually makes more sense that if you're on such a downward trajectory that it'd just continue. Nintendo on the other hand hasn't been nearly as reckless as Sega or Atari and would likely fare a lot better than either of those two did if they were to shed their console business.
I think Nintendo would do well on third party platforms but I also don't think you'd see them make Xenoblade, whether you think that's better for Nintendo or not I guess is up to you.
Edit: And I've been beaten to the point.
