They never said there wouldn't be any more new characters, they said not to expect many more, and in fact we've only had 2 new ones since if we're taking off Echo Fighters, which they clearly don't count as new characters. It's quite different than them coming out and saying "there are exactly 103 stages in the game", after all they could have just said "over 100" if they were still gonna add more.
But yes, I know. Sakurai implied he wouldn't carry on doing Smash after Melee, Brawl, and 4. You can never be too sure with him.
Which is why I said they implied the wouldn't be new characters much like you're saying they implied something, echo fighters do count as they're a different approach to a move set so like them or not they count.