http://www.ausgamers.com/news/read/3563821/phil-spencer-id-love-to-see-mario-on-xbox
We asked him if seeing Nintendo properties on the Xbox platform was something the team could look at seriously, considering Mario and Pokemon are now on iOS and Nintendo has openly said they're looking into the mobile space for other opportunities.
And while we recognise the Xbox One isn't a "mobile platform", it shouldn't be scoffed at so easily, as Nintendo could very well be testing external platform waters. And hey, Microsoft and Nintendo have a very healthy relationship through Minecraft, so the question felt very valid to us.
"I’d love to see Mario on Xbox," Phil says enthusiastically. "As someone who’s been in this industry and played games forever, I’ll still say it: Nintendo has the strongest first-party of anybody. They’re just fantastic and the memories that they have instilled in so many of us, who’ve played their games and had those delightful experiences, having those on Xbox would be great. Obviously we have Minecraft on Nintendo and when that opportunity came up to work with them on Minecraft, you know, some people might look at it and say ‘why would you even do that?’, but with Nintendo, it’s been a great partnership on Minecraft. In fact they put Mario in Minecraft on Wii U with the mash-up skin pack. And continuing to work with them on that and building a stronger relationship... I mean if that paid dividends down the road that lead to something else, that would be fantastic. I know I get questions all the time on would I ever like to see Banjo in Super Smash Bros. and I’m, like, “yes, I would do that in a second”. And certain people think I’m saying that as some sort of PR answer and I’m, like, why wouldn’t you?
Anyway, I’m a big Nintendo fan and I think they’ve been incredibly important for the games industry, they do a great job with younger audiences, and if we ever had a chance to work with them in the future, I would absolutely do it."
I've said it before, with Nintendo moving away from traditional home-only consoles and opening up to other platforms, I think a Nintendo partnership with Microsoft in the next 5-6 years is possible/probable if MS gives Nintendo a sweet deal to do so. And I could also see MS games on Switch.