Short answer:
If Danzo stats with his right arm sealed, Kakashi stomps him.
If Danzo starts with his right arm unsealed, Kakashi still wins since his long range Kamui is much faster than Danzo creating the handseals that are necessary to set up Izanagi.
Long answer:
If Danzo starts with his right arm unsealed, Kakashi will probably attack him and kill him but Danzo will save himself with Izanagi and respawn to surprise kill Kakashi. But Kakashi is too tactical to not have himself be a Kage Bunshin from the start, if he fooled Itachi and fooled Pain, he can definitely fool Danzo; not to mention that Kakashi was able to dodge an enormous AoE surprise point blank attack in Kakuzu's Fuuton when he was busy fending off Hidan, I won't be surprised in the slightest if he could simply dodge Danzo or his attack.
After that, Kakashi will surely understand Izanagi, he is more than smart enough. At that point, Kakashi can trick Danzo, or just Kamui GG him. One Susanoo arrow was too fast for Danzo to make the necessary seals and activate Izanagi (
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). Pre War arc Kakashi could perfectly warp not one but two Susanoo arrows in a single row with his long range Kamui, please note that when the two arrows were already close to him Kakashi still had to activate the Mangekyo and aim and open and close the warp (
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)(
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)(
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); so Kakashi's long range Kamui is a lot, a lot faster than Danzo's Izanagi, if Kakashi wants to use Kamui, he is doing that before Danzo can use Izanagi, hence Danzo is doomed. That's pre War Arc Kakashi.
War Arc Kakashi with complete Kamui mastery, better speed feats, new powerful techniques and a far increased stamina, wins way more easily.
If then you make a scenario where Danzo has Izanagi restricted, well Kakashi simply stomps him.
