Honestly, he will have to be on his own (without Sasuke) for him to even be in any threat. Even then, it was just stated that Naruto alone is possibly stronger than Jigen (who is the strongest of Kara/their leader). I assume Kawaki will come close to that power or just a bit over it in a couple of years (time skip) to carry out the revolution for what he thinks is right. (I think he will mostly agree with Jigen's idea, but will want to do it in his own way. He probably spoke of it before to Boruto, which is why Boruto isn't surprised. Plus he probably is remembering Momoshiki's words to him about his fate).
Kawaki will need to use stealth, as I'm sure his speed won't ever fully match Naruto's. Hence why he's probably going to stay in the village, even after he decides he would rather go through with a similar plan to Kara. I'm thinking he will seal Naruto off to contain him to be brutally honest. It will take a lot of energy to fight against Naruto and then against Boruto. Then again, he did show pretty good stamina due to the bots within him I assume.. but still. Naruto is a lot to handle. So yeah, I think he'll just be sealed. Anyway. He will then have Boruto to mainly deal with (as I'm sure Sasuke will keep a distance so not all of their Aces are lost). Maybe some sort of sacrifice will be made to protect the rest of the village. IE giving Kurama away or something along those lines. Something that would end up costing Naruto his life by his own choice, rather than at the hands of some bitter punk.