I can't say I see how Dixie would automatically be a clone. Yeah, she'd almost certainly be a faster and lighter character with low power like Diddy, but unless Diddy and Sonic are clones, I don't see how that's relevant. Diddy is based strongly on ground control; Dixie would almsot certainly be a mostly aerial character and could plausibly even be a multi-jumper and end up with more similarity to Jigglypuff than to Diddy. That's not inevitable either, but seriously, I can imagine dozens of possible Dixie movesets all of which would play completely differently. It takes a serious lack of imagination to cast her as simply a Diddy clone.
Likewise, if I'm deflating what people are saying, I'm going to stick out there that K.Rool has no chance. He's not like Bowser; in the long run, he's pretty unimportant to the overall DK series, and he's been a mostly dead character since DK64 with all of his significant appearancs being in Rare games that are not in favor within Nintendo. The character offers very little; he was always just comic relief, and while certainly he could be given an interesting moveset, any moveset he could be given could also be given to just about any other large character. I'm not trying to "hate", but I'm telling you from over a decade of playing these games and observing how they're made, I'm pretty sure K.Rool is exactly the kind of character who has basically no chance of inclusion. Of course that's an irrelevant question to Dixie; the whole "reps" system that I think many fans envision is simply not how characters are decided. If K.Rool were a plausible inclusion (and he's not), he would have no bearing whatsoever on Dixie's potential as a character.
As per Dixie's odds? I'd say they're decent, but it's hardly guaranteed. I won't be surprised by her inclusion one way or another.