Just so we are clear, the form you arr speaking of is when naruto is accessing all the bijuu chakra. Since he has full kurama he doesnt need all the bijuu. Though if he wants he could. Senjutsu of the six paths was gifted to him by the sage himself. If sasuke didnt lose any of the power the sage gave him, why would naruto lose it? That would literally make the sage/ kishi an idiot, as sa suke's intentions where not infidelity known and the sage didnt really trust him. Thus it would be stupid to give him a permanent power and make naruto's temporary. Especially considering that naruto was the chosen one/main character.