Danzo always begin his fights with Izanagi, when Kakashi always begin his fights with Kage bunshin or kawarimi when he has no knowledge about the opponent real power(Choza said it). So they could actually neutralise themselves at that time, the time, Kakashi begins to analyse Danzos jutsu. And knowing how smart Kakashi is, he can actually begin his analysis and find how Danzos jutsu works(but i think he will need to see 2Izanagis at least to understand). Even if he actually doesn't understand quickly, Danzos Izanagi contrary to the popular belief is not that powerful or unavoidable, why?
- When Danzo uses Izanagi, he is forced to attack during 1minute, since his Izanagi only last 1minute and if he did nothing during that time, he will lose his first Izanagi for nothing. So he will be forced to use another Izanagi and so on. So if it continues that way, he could lose 10Izanagis during 10minutes for nothing. That's why he must be skilled when he uses Izanagi. He must know when to use it, but like i've said, Danzo like to start his fight with Izanagi(since he did it against Sasuke).
So during the time he fights Kakashi's KB, it's not even sure if during one Izanagi for example, he will be able to defeat him during 1minute, especially when i see how careless Danzo is when he is in Izanagi mode(got even killed by shurikens).
Danzo has advantage with his futon it's true, but having elementar advantage doesn't guarantee a win. Sasuke actually beat him with a raiton attack(facing a fuuton attack from Danzo) when he didn't had the elementar advantage. So it depends how skilfull you use the technique. Danzo doesn't use sharingan to predict movements. It's where Kakashi could have the edge. Raikiri in the heart could kill wheter you have the elementar advantage or not.