Board Thread:Site Discussions/@comment-5711801-20131006095325/@comment-4236081-20131007161435

Kagimizu wrote: Unfortunately, we aren't likely to see Snake. Let's look at some of the recent characters added: These three characters were added in at least in-part for publicity reasons. Snake on the other hand only has Metal Gear V: The Phantom Pain, which isn't coming out on any Nintendo console. Sonic had the fortune of Sega and Nintendo's exclusive publishing deal making him a very viable option, despite his third-party status.
 * Mega Man: Long-time fan favorite and one of the most desired inclusions in the franchise.
 * Olimar: Profile links to the Pikmin 3 official site.
 * Toon Link: Profile links to the Wind Waker HD official site.
 * Sonic the Hedgehog: Profile links to the Sonic Lost World official site.

Also Brawl concept was to add those characters which appeared in every single Nintendo consoles.4 concept is to add 3DS and WII U characters.Very unlikely for Snake.