Kaguya can one shot naruto and sasuke too. But in the end they'll still win.
Just like they did to Jubito. he could've defeated them. but plot let his emotions flow for some reason.
Sasuke defeated Itachi and won this battle. DWI
Its different in the Kaguya case than the Itachi case.Kaguya is not dying already,nor will she refrain from killing Sasuke and Naruto at all.
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This ^ image is 2 seconds before Itachi died.At that time he had his full susano's along with Totsuka blade and Yata mirror activated while Sasuke had no place to run, was chakraless and was scared to death.After Itachi touched Sasuke on the forehead he died and his Susano reduced to lower stages and finally dissapeared.
On one hand Sasuke was chakraless,sharinganless and jutsuless while on the other hand Itachi had MS and Susano activated before Itachi died,the Susano too deactivated after his death.If you can still say Sasuke won..then -sigh-