Remember kids: ideally Nintendo wants 2 big holiday games; one to appeal to children/families, one to adults.

This year it's Smash for gamers, Captain Toad for kids.
Next it will be Amiibo game for kids, Zelda for gamers.

In terms of scale I think this type of game would be more of an A-tier Nintendo IP in sales ... meaning Mario Kart or Smash Bros. type numbers. 

Zelda, just isn't there, I also think it's probably a 50-50 shot that Zelda ends up getting delayed. Supposedly this is going to be the biggest Zelda game ever and the first one using HD assets/engine ... that smells like a delay just waiting to happen. 

At least if it does get delayed, they still have an arguably even bigger title that can carry the holiday season. 

The 3DS also needs a big fall 2015 game, so this solves that issue too. Like Smash U/3DS you'll have Amiibo Universe (or whatever they call it) on both systems. Of course they want all Wii U and 3DS owners to start buying amiibos. 

Nintendo's made Zelda their big holiday game before, and I don't think 2015 is any different.  I also think the idea of an Amiibo game that features all the characters would just tarnish their IP and water down the gameplay elements that make their franchises so great.  Smash Bros is a fighting game so it's fine, but I don't see how they could pull off another style of cross-over game without risking turning into Disney Infinity or Skylanders.  Nintendo doesn't like to copy other people, they prefer to do their own thing and surprise people by doing the unexpected.  Take Captain Toad as an example that no one saw coming.  The fact that so many people think they should do an Amiibo Universe game probably proves that they won't do it.

I'd love for this to happen but we all know how stubborn Nintendo is. Don't get yer hopes up.

Well the "we don't want to copy" ship sailed a long time ago, pretty sure everyone knows amiibo is Nintendo's take on the Skylander's concept, I don't think anyone in their right mind is going to say "wow! I've never seen this concept before ever!", and Nintendo knows that, lol. Hell, they had a Skylanders Wii U bundle themselves last year. Not only is Nintendo not even first to this idea, they're not even second, Disney beat them to the punch too. So that's something Nintendo just is going to have to accept. 

To be honest the Skylanders games are pretty damn well made for what they are (basically a toy commercial). I played it with my niece who's crazy about Skylanders and I was surprised how polished the story, graphics, and music were. Gameplay was pretty fun too. 

A Nintendo version of that would sell like gangbusters, easily as much as Smash IMO. Fighting games are inherintely complex especially for kids, it's also according to Sakurai very difficult to add playable characters to the game because it takes months of work to balance the game engine. So Smash probably isn't the ideal amiibo game. It doesn't neccessarily have to play the same as Skylanders though it could be more like an RPG (ala Pokemon) for example. Or maybe it could be like a Subspace Emissary: The Game. Heck maybe it could be Nintendo's (cartoony) take on Grand Theft Auto, just set in the world of Nintendo (just as Splatoon is their take on the FPS genre and Pikmin is their take on the RTS game). 

They'd better release an Amiibo specific game quick, if they don't want the whole thing to fade into obscurity.

Always mindboggling to me when people say they think that Amiibos will move systems this holiday season, why the hell would that happen? The reasons for getting those things are severely limited at the moment.

What if it is a Nintendo Land type of game and you can buy the core game or the "episodes" for your favourite amiibos - or at least the ones you own?
Mario and Luigi can have their own mini-game; Toad can have more Captain Toad levels, etc. etc.

Of course, all these games would be based (graphics and backgrounds) would be based in the amiibo figures.
Just like we had Sonic DLC based on Yoshi and Zelda.

That's also the other problem with Smash as the "hub" game (for now). They can't do the "scan in character and now he's unlocked" because the Smash community would murder them for basically locked DLC for a well known established franchise. So they're kinda stuck doing the "non-playable friend" idea. In effect they basically can't let the amiibos do too many cool things, because then you'll inevitably have some angry people who don't want to buy amiibo that feel like they're locked out of certain functionality. 

But a new franchise IP made specifically around the amiibo concept? Well that has no rules, actually in fact the Skylanders series already set the rules, so having to buy a toy figure to unlock the character in that type of game is not only acceptable to gamers in this context, it's part of the fun. 

The Skylanders/Disney Infinity "genre" of game is by now established, so perhaps it would be smart for Nintendo to stick closely to this concept. Complaining about having to buy toy figures in this context would be like complaining about having to use plastic instruments in Guitar Hero/Rock Band ... it would just be non-sensical. So this genre kinda would give Nintendo "cover" from that type of criticism. 

I hope for Nintendo to make lot's of money

Captain Toad is not for kids!