Why so certain? Toad's certainly an important Mario character and has been for decades, but the moveset potential for Jr. is far more interesting, and in the more recent years he's been more important to the games he's been in than Toad, even if Toad's been playable.
As for a new Mario rep, it's been two games since Mario's gotten a rep, and in fact he lost one in the previous game. I don't think it's unreasonable to think that their flagship series will get a 5th character.
K. Rool is not as likely as Dixie Kong.
Again, don't be so certain. K. Rool is just as likely, especially since we don't know of his involvement in Tropical Freeze yet.
Ridley is, due to recent events, not super likely.
Time for me to be overly certain- that quote meant nothing. It was simply providing contextual and atmospheric text to the stage itself. I assure you, it meant nothing.
So... new here... what do I do?
Ike and Lucario have absolutely no reason to go; why cut them over Wolf, Lucas, or Toon Link? (Not calling Wolf or Lucas clones, mind you, but they are at least vaguely similar, whereas Ike and Lucario are completely unique- none of them should be cut, though, IMO).
Mewtwo has absolutely no reason to go; why cut him over Young Link, Falco or Ganondorf?