Considering how brilliant he is as a strategist, there's a possibility that he may have come up with ways to beat them. I can't think of any, but that's his job, he's the genius after all. He said that in battles he does plan 100 moves ahead. We'll have to wait and see how well he does against Tayuya.

And anyway, who says that either of them actually WANT to become jounin? Both of them are probably content as they are.