I've long predicted that Snake would be unlikely to come back and I have not wavered.
I really liked Snake in Brawl and he was fun to play as, bringing uniqueness to the roster. The codecs were also humorous and emphasized the wackiness of having a more realistic character in the middle of fantastical, cartoony ones. The MGS music selection was memorable and Shadow Moses Island was a great stage.
But things have changed. This isn't 2006 or 2008. Things have changed in the past years. The situation with Konami and Kojima doesn't help at all. The business relationship between Nintendo and Konami isn't as good as before.
I like Snake. I would love to see him return to Smash 3DS/Wii U, but let's be realistic. Snake's chances aren't favorable. On the contrary, there are more obstacles to his inclusion than before.
For now, the only character I want and find viable is Wolf. Any other character (veteran or newcomer) will no doubt impress me and, hey, it's one more character to try out and play as.
I find it very difficult to dislike a fictional character as it takes a particularly repulsive characterization for me to harbor negative feelings in the first place, so I doubt there's any viable Smash addition I'm going to outright dislike.