What you think and what Nintendo is thinking or what they will do, are two different things.
First, smartphone gaming become bigger than console gaming and Nintendo couldn't ignore it any more, second, we dont have real Nintendo games on iOS/Android, those are smartphone games not full Nintendo games, and third, Nintendo was very clear about why they releasing mobile games, because they want in that way to make bridge between mobile and full console games and to use it like market tool for Nintendo consoles and their full games. If you release Metroid Prime on on Xbox thats one reason less for some people to buy Nintendo console and than people would be start expecting also another Nintendo IPs on Xbox.
In any case it won't happen, it's not realistic scenario at all.
Are you looking closely..
I have followed Videogaming from the start.. And from where i'm stand.. I think MS and Nintendo working together makes very much sense for both companys.. Not only becourse Switch and One are the most different "consols" that we have ever seen i Videogaming.. but mostly becourse of the next 10 years and future to come.
First of all.. I'm 100% sure that the biggest reason MS started Xbox.. was an atemt to (with time) to be like android and ios are for smathphones for TV's.. Meaning earning money on lots of other things than games.. With how good the smartphones has become and things like cromecast.. that marked is gone. MS have tried again and again to break into it with Windows mobil.. Not with any real luck..
We all know that pc's are becomming less and less important for the mass marked and MS can see that even windows will face a hard time against android and ios the next 10 years.
Then there is Nintendo.. Nintendo has by fare the most apelling gaming ip's for the mass marked.. but they are only good at games.. not all the other things that people today expect.. the online infra stucture.. OS and PR (outside gaming) And they also lack the contacks MS have.
And now it comes..
I could see MS.. Nintendo and even Nvidia making a "total partnership" (not that money should be split in 3) where they try to take on ios and android.
Nvidia.. does not earn any today outside hardware.. so for them it would makes sense.
Nintendo.. can get a much better deal.. than just selling on android and ios.
MS will have a "final shot" to be relevant in the future.
Wii sold 100m, DS sold 155m, 3DS will end up around 75m, and now seems that Switch will be huge success, without MS. Nintendo doesnt need MS, MS is one that is becoming more irelevant on console market where PS4 killing XB1 and where all MS IP are also avalible on PC.
Like I wrote, In any case Nintendo IPs on MS console it won't happen, it's not realistic scenario at all.