Because I am a crazy person, I'm going to list some reasons why I think Snake might be coming Monday.
1. Maintenance is happening mere hours before MGS5 releases. If Snake makes it to Smash 4 at all, there is no time more opportune than now. Also, its something that I imagine Konami would have mandated. The hype is real and releasing Snake now would be a win-win for Nintendo and Konami.
2. Pretty much everyone agrees that the update at the end of July was a little sparse, especially coming off of the massive June update. Here we are exactly a month later with another potential DLC update on the horizon and its happening much sooner than expected. Why have two updates so close together if you could've had one larger one if only you had waited? Well, if Konami was hypothetically adamant about Snake releasing right on MGSV-eve even if he was completed a month prior, its possible that Nintendo would just go ahead and release everything not-MGS related once it was done, hence the most recent (somewhat light) update.
3. "Kept you waiting, huh?"
4. Man, I miss Snake