I think there's a time in every Japanese game developer's life that he has to face the music and make Ridley playable. I don't want to resort to this argument, but really, "Why the **** not, man?". He really has no reason. He knows how insanely popular Ridley is in the West. He'd have to. He knows that people want him, and have wanted him. He's even acknowledged that he'd be possible, with some work.
I'm sure there was a time when he would've said "Ice Climbers? Haha, that'd be pretty impossible, I think. You couldn't possible control two characters at once!" or even "Pokemon Trainer? Are you kidding? That's three characters on one slot!". Let's all be completely honest with ourselves here. There is no reason in hell beyond A. blind stupidity or B. complete, childish stubbornness that Ridley can't be in this game. His size isn't an issue. It never was. He can be the new biggest character, even sized-down, because really, Bowser's not that huge, and neither is Ridley if you disregard his wings and tail (which don't necessarily have to have hitboxes and both can be curled up until use). Yes, he's huge in the Prime games. But really, in most of his 2-D appearances, he's not that much bigger than Samus (save Fusion, who wasn't even the actual Ridley) and it wouldn't be a huge stretch to return to that, especially since we're getting centuries-old Megaman and such.
All-in-all, if Ridley doesn't make it into this installment, with all the demand and drama, I think it's time to lose all hope in him. If Sakurai doesn't put him in this one, he's not getting in. End of story.