My case with Snake and DLC stands as such:
What has changed from the main disc for Snake?
Of our 6 Brawl cuts,
Two were cut due to the separation of Transformation fighters,
have had an interview dedicated to explaining why technical limits kept them out,
one in the game due to high popularity....
one who will very likely be the same,
and one that's... just been lost. No real reason given by Sakurai, Nintendo, Kojima, or Konami.
I can't specifically remember when, but sometime between E3 2013 and 2014, Kojima replied to a fan question about Snake in Smash with something along the lines of "I'd love it, but Sakurai hasn't approached me or Konami about it... yet." Fast Forward to E3 2014, when Sakurai says at the roundtable that there was at least a tentative roster for Smash 4 drafted up (with likely having Roy, Mewtwo, Lucas, and maybe Wolf on it but certainly not Lucina, Dark Pit, and likely Doc at the time) before work ever got put forth on the game.
Call me out if I'm straw grasping but I took that to mean that either Kojima was being the "troll" that he is known for to surprise people when Snake turned up later on the main release.... or... Snake had just been dropped.
Since then, Kojima's left Konami and the company itself has made some fairly radical steps away from main gaming as we know it which has given the company an EA-level sour eye in the community. Which could be a whole bunch of conjecture that means nothing. We have the ballot, which we don't know exactly how it works and assume its more of a "suggestion box with volume" instead of a simple tally of votes. Sakurai has stated that we will have "only several more characters," through DLC and that it'll be a LOT of fanservice (and not in the Senran Kagura way) for the fans from here.
If Snake is to return as Smash 4 DLC, the way I see it having to come is that either recently or in the very near future, Nintendo's going into strict contracting with Konami about the rights (to avoid a
time lapse situation) to even BEGIN work on him and would end up being basically the very last character to come.
Snake, among Icies and Wolf has to be the top 3 most requested veterans to return. And probably even a top 10 overall requested. However, the somewhat enigmatic bubble of contracting I feel makes him more likely to return in Smash 5 due to his popularity than to be crunched in with Smash 4.