The Smash Bros series, since the beginning, employed emblems to signify the universe, especially more so when it's shared by multiple characters. For example, a picture of the earth is used for the Mother series, since that's included in the title logo, or that the Pokemon's emblem is the Poke Ball, the most commonly used item in those games. Some of the other emblems are character-specific or game specific though. For example, F-Zero's emblem is a falcon, which is basically only used for Captain Falcon.
That is to say that changing emblems between games isn't an impossibility. Snake is an example. Previously it's a lightning fox emblem, but it's since changed to an exclamation mark emblem. Taking something I thought might be up for changing: in case Smash decided that Captain Falcon isn't going to be the only playable character from the F-Zero universe, I can see the "O" in F-Zero being the emblem (because it looks like a zero) instead.
Personally, although the mushroom is emblematic to the Super Mario series, I have always thought that it's interesting that it's not an "M", since Mario's peers (Donkey Kong, Yoshi and Wario) used their character emblems for their universes. I know Mario is not just Mario, but it's more of an observation.
Do any of you think the current emblem choices are appropriate?
Thank you for reading.