It's Sakurai's trolling.
Today he showed what he is truly capable of in doing fake-out confirmations.
He blatantly said "Unfortunately, Zero-Suit Samus will not be returning in the next Super Smash Bros. game" while it showed ZZS's Brawl artwork fading into black-and-white.
Then it goes back to color as he says "Naaaa, I'm just kidding. She's coming back."
This was the most obvious troll he's ever made. He specifically said a character isn't returning IN AN OFFICIAL ANNOUNCEMENT and then said "JUST KIDDIN'!"
The fact that he showed Ridley's shadow, and not his actual body could mean something. Yes, you could argue that he didn't show his body to make it more ominous, and to get people on their toes, but others believe that Sakurai strategically did it, so since he wasn't actually showing Ridley himself, he wasn't making an official character reveal and wouldn't have to say that he is playable.
Playable or not, we'll most likely find out at E3. If not, then in the Summer, when the game comes out.