So I have mentioned this a few times, but I would love to see a futuristic adventure game starring Captain Falcon, where you collect bounty and fight bad guys. The combat system would be inspired by the Arkham games and would have side missions with F-Zero Races.  
I don't know why, I just think Captain Falcon could have an amazing story and his character could become something more.

Anyways, what do ya think? 

What would your dream spinoff be?

Nobody has any ideas? :P

You pretty much took the idea from my head.

Other than that.

Starfox in the form of Warhawk - massive online battles
Fire Emblem MMO - more of a 3rd person action game like most MMOs today.
Pokemon fighting game - wait...
Pokemon Snap - ... oh
Pokemon Tamagotchi game - does hey you pikcachu count?
Advance Wars or Fire Emblem Tower Defense game - I really like the genre and wish there were some on 3DS.