They said it would be on the rumored 20th direct. Given awkward names like Samus' Revenge and the like, it was probably fake regardless. Still, if we all agree it;s probably not happening, is there really any harm in entertaining the thought just a little?
I'd suggest Reimu, but she's not exactly ignored anymore, is she? I still think she's slept on given Touhou immense popularity in Japan, but she's acknowledged fairly often nowadays and she's not unexpected anymore. As for actual sleeper picks...
Ezio is seriously ignored, despite Assassin's Creed being huge for Ubisoft. I'd imagine Rayman's cannibalizing all the Ubi support, isn't he? On that note, the Prince of Persia's pretty ignored too, even if he's a lot less likely.
Bill Razer is also massively slept on. Contra's an NES classic just like Mega Man and Castlevania, and it's what popularized the Konami Code. You'd think he'd get more attention, but nope. Nobody talks about him. On the topic of Konami, Raiden would be awesome, and a great way to bookend Snake being the first third-party guest in Smash. Alucard would be sweet as well, but there's less he could bring with him.
Also, Civilization. That's right, Nuclear Gandhi for Smash. Admit it, you want it too.