Yanno', I recalled last year the creative teams were teasing they have a character in mind for this year that'll blow everyone's minds/break the internet etc...I hope either of these characters weren't who they were talking about, as that's a bit of a letdown.
As a preface, Judge Doom is an iconic villain, no doubt about that. But not mind-blowing to see him as a character, not that hard to dress someone up in all black. Now if they wanted to get intriguing, they'd be showing off his Toon side and that would be more interesting to see how they pull that off.
As for Yokai, pretty obvious they're doing this to tie in with San Fransokyo. As with Judge Doom, not a hard character to dress up. And he'd only be interesting if they'd have some sort of effect for the nanobots.
EDIT - It just hit me that if I'm gonna' mention these two characters as being a letdown if they were being hyped to blow our minds, I might as well give what I think would've actually lived up to the hype. For me, that would be a character that is not only fitting for the event, but at the same time feels like a fat chance in heck that they would ever be a character in a Disney park for a multitude of reasons.
Mickey...possessed by Julius a la' Runaway Brain. Now that would send me (and probably many others) for a loop. There's also an easter egg in the queue for Runaway Railway of Dr. Frankenollie's newspaper ad, so they're still acknowledging it exists.