Dude, change your poll it doesn't match your thread title at all.

I can't see Zelda, Metroid and others niche games selling that much more but Mario Kart itself can sell over 50 million if multiplat.

Your poll and topic completely fail to match. Also it is obvious that Nintendo would suffer being a software only company. They offer a compelling product that people want (Their first party games) and tie that in with their hardware, that combination alone is likely more valuable than any software only scenario could ever be.

They would sell less. They would then have to compete with third party games.

They would sell well at first but the costs of developing on other people's hardware would ultimately mean Nintendo like Sega would limit their experimental/niche games, so we would get a lot of Mario spinoffs, a Zelda or two and fewer everything else. If they went the mobile route, they would start releasing cheaper games with less depth due to budget issues and "free 2 play" games built around milking people.

Nintendo itself may survive but it will be a shadow of itself and people would still bitch about its games being the same but this time they would be correct.

Some games like Metroid or Zelda and maybe even smash bros would probably have an increase in sales. But I doubt games like Nintendo land, nintendogs, Kirby etc would increase.

Exactly see Sega and the decline in quality in  their games/franchises as a perfect example.. 

I'd say that their A and B games (mario, mario kart, SSB and Zelda, Metroid and Donkey Kong) would sell more than they do now, if released on playstation and/or xbox - but their C games (kirby, yoshi etc) would sell less.

What I don't understand is why they don't release OLD games on iOS/android; super Mario bros 1-3 would sell like gangbusters!

Because they'd damage the money they make selling it on Nintendo's own digital methods if they did it on iOS or Andriod especially at lower prices then they currently do it for.

I think they would do worse but Sony or Microsoft might of wanted to buy them out if we got that far. i hope we don't get there. I don't think the success of the 3DS will lead to that