I agree that King K. Rool should not work with the Kongs in a game in the near future. He really needs to cement himself as an iconic villain for the newer generation of gamers that got introduced to him with Ultimate. If they make him help out Donkey Kong in the next main series game, it may give the impression that King K. Rool is more of an eternal rival than a sworn enemy. I can't imagine that King K. Rool actually likes the Kongs at all, considering how he tortures them, uses them as living batteries, and attempts to nuke their island. In comparison, Mario and Bowser seem to have some sort of mutual respect for each other. Bowser never attempts to actually kill Mario or Peach, let alone show any interest in doing so, while Mario always makes sure to invite him to his go-karting and sporting events. It seems to me that whenever King K. Rool and his kremlings do something with the Kongs, like Barrel Blast or Super Sluggers, it's because he wants the spotlight over any sort of sportsmanship, at least from my interpretation.
All of us that are in our 20s to 30s know how awesome King K. Rool is, with appearances in the DKC trilogy, DK64, and even the cartoon. Spin-offs aside, King K. Rool hasn't had a major appearance as the main villain since DK64, and that game is two decades old now. I trust that Nintendo can understand King K. Rool's character enough to make him memorable again, they already did a great job with his portrayal in Ultimate. It's just a matter of when at this point. Personally, I think King K. Rool's role in a future Donkey Kong game should be the most similar to DK64, in terms of how often he appears. Seeing King K. Rool comment on the bosses after their defeats was interesting, and it made me really curious on how the final confrontation between the Kongs and King K. Rool would go. I think a similar approach for a new Donkey Kong game could really flesh out King K. Rool's character, and make him stand out and leave an impression throughout an adventure.
With all of that said, I'll humor the idea of King K. Rool actually teaming with the Kongs. If that does happen, he would probably scheme something behind their back throughout the adventure. As soon as they take out the new big bad of the game, King K. Rool would reveal that he wanted to weaken him on purpose so that he could take over instead. Then there would be a last world where you have a final showdown with the kremlings and King K. Rool. In a way, it would come full circle considering his fake kredits in the original DKC. That's the only way I can personally see King K. Rool teaming up with the Kongs working out. He's not the kind of guy who would let Donkey Kong get any kind of credit for saving the day.
