Minato's speed is so immense that it even left the strongest characters like Hashirama and great shunshin users like Tobirama in the dust. Not only did he arrived much earlier than them on the battlefield, but he got time to spread his kunais around something as huge as the Juubi, go to a rock in middle ocean(somewhere around the battlefield) to put a kunai, come-back to warp Juubi's Bijuudama there, have a speech in a while with Naruto and Sakura, all that before they actually appeared. Those same Hokages managed to distance Sasuke's group. Same Sasuke, a Itachi who was trying his best to meet Kabuto as fast as possible was incapable to distance.
So i think it's not far-fetched to say that Itachi could be blitzed by Minato anytime soon during their fight. Minato's shunshin, speed, reflexes are so much advanced that even Tobirama was so baffled that he could barely say a thing, funny since he is that much amazed when he didn't even infact saw the bolded part happen. Wonder what he would have said if he had. Maybe he would have caught a heart-attack XD
And this is in base, because in KCM, Minato should even be much faster. Naruto who only had a regular speed, managed to keep up with the fastest ninja alive with his maximal shunshin speed in KCM. So for someone like Minato who was already considered as the fastest ever, KCM would improve the gap that already existed with other contenders.
He can also redirect almost any attack as proven when he redirected the most powerful attack we've seen in the manga so far in the sea while moving, which is really an impressive feat. He also showed that he is capable to put his markings on random areas like rock middle ocean, so it's definitely possible for him to have put/put one in a volcano as well. In this case, warping Itachi there(Susanoo or not) and it is GG
Adding the tanking feats/durability that KCM gives to it's user, and it would even be difficult for Itachi to even hurt Minato(if miraculously he even lands a hit). With the chakra arms, it also gives to Minato a mid-long range attack and allows him to put his markings from a distance, rendering not only the close, but also mid-long range fight against Minato even more dangerous
It's unknown though whether or not, Minato could use TBB, but judging by the fact that he is already capable to shape his chakra in to the ultimate form(rasengan) in human form, rasengan being based on TBB, i don't see why not. In this case, it would only increase Minato's fire power during the fight
Normally, Minato has all what it takes to win this fight quite handily, except if Itachi smh manages to put someone as fast as reactiv as Minato in tsukuyomi, which is greatly unlikely
