You know, whenever the discussion of Nintendo and 3rd parties comes up, a vital element of it gets usually (and conveniently in some cases...) ignored... Handhelds. For a lot of Nintendo fans, handhelds are part of their steady gaming diet, with not only plenty of support from Nintendo themselves, but also a ton of 3rd party support. And for anyone that plays Japanese games, a Nintendo handheld becomes just as much of a must have as a non-Nintendo console, specially DS and 3DS. Do Nintendo fans in general need more than this ? I don't think so... And if you do, there's also PC to consider here, or those who just play other consoles through friends and such.
Basically, I'm skeptical of Nintendo fans being more prone to get another home console than other gamers, and I believe it's more of an individual choice than anything, with factors such as gaming budget, personal taste, and time to play games being crucial here. Hardware sales can indeed add to your point when they favor other platforms, but then again, the same could be said of Wii, DS and 3DS, yet people usually talk about there being different demographics when it comes to those... So, which one is it ? Different demographics or multiplatform gamers ? The truth is probably somewhere in the middle, and without actual data, we can only speculate.
I'm also of the opinion that the issue gets a bit overblown in general... I mean, sure, too many 3rd party "AAA" games skip Nintendo consoles, but it's not like there's nothing to play... You still always get a good share of exclusives and ports, like Sonic, Monster Hunter, Resident Evil, Tatsunoko VS Capcom, No More Heroes, Lego games, Just Dance, ZombieU, Watch_Dogs, Project Cars, Harvest Moon, etc... So, it depends of what kind of gamer you are.
Well, as much as I think Snake was not the best choice for Smash, he still arguably had some relevant history on Nintendo platforms, so he's far from being the worst choice. It would've been far worse if someone like Cloud got in for example, without ever being before on Nintendo. So, as I said before, I think the requirement should basically be to have a significant history on Nintendo platforms and be a good fit for Smash. You can be a bit more selective in the future and be certain that whatever character you choose has a good reason to be there, with a strong bond to Nintendo in one way or another. I would definitely disagree with using Snake's case as an excuse to fully open that pandora's box and just let any popular character in... But of course, it's not up to me anyway...
In any case, Smash will always be about Nintendo first and foremost, and Sakurai makes this quite clear when he says that the likes of Mega Man are special cases, limited from the start. Whoever gets in in the future, it will not change that.
I'm not sure what you mean by "veteran" here... If you're refering to his long history, let me remind you that Simon and Bomberman have existed since 1986 and 1983 (1985 on Famicom) respectively, being among the first 3rd party characters on Nintendo platforms. And Bomberman in particular has appeared on pretty much every Nintendo platform since then...
ive own every handheld Ninty made. IMHO 3rd party is nto that relevant. Firstly cause western devs never really messed with it and def arent not. and how well do those games do? Especially in comparison to Ninty's own titles? Are you really going to tell me that the handhelds make up for the lack of 3rd party on consoles? Come on, they are not even the same games. Where are the AC, COD, MG, etc. ANd when I say where are they im not talking some 2d spinoff. or old port. Even with PC you still miss stuff. I find it hard to believe that all those franchises that skip the system most Ninty fans dont want to play them. I think sales says otherwise.
The truth is somewhere in the middle thats true. I bring up demographs for WIi because that was a blue ocean machine, there were not blue ocean machines prior to Wii. Look at the best selling software versus the HD ones, VERY different. The portables that has always been Ninty's field they never had any real competition until PSP and even then.