And is it possible that the three are currently talking to Nintendo about why they should make games for only their smart device systems? Even if Nintendo is planning to have their own eshop app that must be accessed to download their games* Apple and others may want Nintendo to only release it on their devices. Or they could want a time exclusivity of their games. Imagine if Apple got some of Nintendo smart device games first in some sort of time exclusivity and started advertising them on TV or even their press conference O_O One valid reason why Apple and others will not want to have exclusive Nintendo games is the the fact that Nintendo hasn't made one yet. In other words, they could still be in a wait and see mode.

The other side of the question would be if Nintendo should think about entering these exclusive deals even at this time and is time exclusivity for their games a better alternative if Apple/Google/Microsoft will still give them a lot of money for doing so.

And if you're wondering if Apples and other are actually fighting over exclusive app games, they are: http://bgr.com/2014/04/21/ios-vs-android-exclusive-games/

*It is not confirmed that Nintendo is planning to have an app that needs to be accessed to download their smart device games.

No, not worth it in any sense.

Yeah most phone market providers do not care enough about the market more than it is another source of revenue. I don't really think they have made deals with any other developers to make them exclusive, it basically been up to the developer.

Actually, Apple has made the Infinity Blade franchise exclusive to iOS http://www.pocketgamer.co.uk/r/Android/Blood+%26+Glory%3A+Legend/feature.asp?c=56905

Apparently here are the top ten exclusice iOS games: http://m.imore.com/top-ten-ios-games-exclusive

Gaming apps are the most often used apps in smart devices as well: http://www.emarketer.com/m/Article/Game-Apps-No-1-Amazon-Apple-Google/1010739

It might make a little sense as a timed exclusive to raise the profile of a new phone by an otherwise obscure brand.
Windows phone would benefit a lot. It could send a message that windows phones has games.

I'd be pissed off as I currently have a 3ds a wii u and an iphone 6 plus and I'd need yet another phone to get Nintendo stuff.

But Apple and others have been fighting over exclusive games and Apple has been gaining time exclusivity for popular games like Plants vs Zombies and Cut the Rope. 

From: http://bgr.com/2014/04/21/ios-vs-android-exclusive-games/

"Apparently Apple, Google and Amazon are engaged in a fierce battle for scoring exclusive games, which could convince certain smartphone and tablet buyers to switch sides in order to play a certain title."

“When people love a game, and it’s not available on an alternate platform, they’ll change platforms,” Kongregate head Emily Greer said.

 “Apple doesn’t offer money for game exclusives, only marketing or promotional assistance, these people said.

I think Nintendo may be an exceptiom for Apple though if they're interested enough.

I can see Apple being interested and Nintendo might go for it - there are quite a few games that are pay-once on App Store that were met with success, so the audience is definitely there.

Windows Phone would benefit the most from it, and I am guessing MS want Nintendo games under the XBox brand on PC. I'm not to sure Apple or Android will try to get exclusivity.

No, the never bought a game as an exclsuive for their OSs

What would be the upside for Nintendo? There is absolutely no upside. Those apps/games are supposed to help sell dedicated gaming system and their games, Nintendo needs to put them in everybody's hands.