This Smash Bros. is definitely less about relevancy than any previous Smash Bros. before it. It's more of a celebration of its own history as well as the history of Nintendo itself (If the redone stages are any indication). So, to me, signs like that only point to K. Rool having a greater chance, because relevancy was his biggest road block of all... And relevancy used to be a HUGE roadblock.
I'd be happy if K. Rool made it in, though I'd prefer Dixie, Cranky, or Funky, but I'm a big DK fan, and K. Rool would make me overjoyed. I was just never a huge fan of the character back in the day, and I wasn't as bothered by his removal over a decade ago as some other DK fans were. But sure, you can count me in as a supporter.
When it comes to characters feeling "likely" or "deserving", I think of three categories; Relevancy, popularity, and importance. Some characters share all three, those ones would have the best shot, but this time around... I don't think there are any potential newcomers that have them all, except maybe Spring Man or something, but I suppose a character could be too relevant to where it harms their chances too. K. Rool has popularity and importance covered, and he's very popular, and very important. Popularity would get like, a 10/10 (that Mii Fighter costume was proof they're listening too), his importance probably an 8/10 with him being the main villain of the DK series (just not the only villain), and relevance, oof, probably a 2/10 (that Mario Odyssey name drop sure was something, wasn't it... heh). And he's not exactly a "retro" character, so I wouldn't lump him in with the likes of G&W or Duck Hunt, characters that represent their own games or franchises. His chances seem good though, but, y'never know with this series. The ballot could be what gets him in, probably helped with Ridley, but also, Waluigi probably did well on the ballot too and that didn't work out for him (not to mention Waluigi isn't as important to the Mario series as K. Rool is to DK's)... So who knows. Nothing is guaranteed.