Here's a concern i've had for a while that could potentially affect Snake's return:
If i'm remembering right, in an old Iwata asks, Iwata spoke about how at first he was very skeptical about Snake, feeling like he was much more of a Sony character. But he eventually lightened up to Snake and felt like he was a great fit for Smash.
Now the concern i've been having is that what if the new president is not as open to Snake as Iwata. He might feel as if Snake shouldn't be in Smash because of his ties to Sony, regardless of Snake's presence in Brawl. I just really hope that's not the case.
Snake was a very popular character in Brawl, so I feel like that should be more important than his history with Sony. To me, Snake doesn't represent Sony in Smash, he represents Metal Gear and the Stealth genre. And with the over-the-top wackiness of the Metal Gear series, Snake is the perfect representative of the Stealth genre for Smash. Snake's presence adds a lot of uniqueness that feels missing in Smash 4, and no character can replace that.
EDIT:
You know what I really want? Better music. Not that the music in Brawl was bad, but most of it was forgettable or just didn't fit (I'm looking at you Calling to the Night).
You mentioning that song actually reminded me of one of my favorite Smash moments.
I was in a local Project M tournament, and I was up against one of my friends who was also a Snake main. He was probably the best Snake main I ever played. I chose the Solid Snake alt, and he chose the Big Boss alt. The tournament went by traditional tournament rules, but we broke them for this match. We picked Shadow Moses Island as the stage, and switched the music to Calling to the Night.
The battle was intense! I remember us both being high percentage on our final stock. We were juggling each other, desperately DI-ing to avoid death while song was at it's climax! At the end, I stuck my friend with some C4, up thrown him, and finished him off with some C4! The crowd was cheering, and instead of shaking my hand, my friend saluted me and said, "You are the successor to Big Boss!".