Yea it can burn fire, but that fire was a set amount so to say... you can restore that chakra shroud as long as you have chakra... and the Kiuby has tons of chakra...
And also when Sasuke used it against Raikage who had his lightning cloak on, his arm didn't burn instantly, it took some time before raikage cut off his arm and he didn't show signs of pain or anything of that matter, the flames didn't even expand over the rest of his body:
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And even if it is big, it doesn't matter if sasuke can't keep up with it, and Right now Naruto in BM is the fastest ninja alive, he was able to counter all those TBB fired from almost point blank range in a split sec:
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Unless the EMS boosts his ability to follow high speed then he can't follow Naruto's movements.
the battle between naruto and sasuke wont be easy win. the whole series is building up for this battle. most likely They're setting Sasuke up for the Rinnegan and Naruto as the Juubi Jinchuuriki.
in essence it be like a ultimate battle.