That is impossible for obvious reasons. Despite your lack of proof of stating he lost it, it seems that you carefully ignore that Naruto did use Sage powers from RSM in his other forms, such as flying. The only reason why Naruto never used RSM was because he didn't need to.
Your argument about Sasuke using the Rinnegan is invalid as-well, considering the early trailers of Naruto the Last, Studio Perriot designed Sasuke without his Rinnegan on, nor his Sharingan. Meaning that either Sasuke can deactivate it, or the former: They edited the Rinnegan in later. If that was the case though, Kishimoto would not need to draw hair over Sasuke's eye :sdo:
Naruto has half of the Sage's chakra.That's why he has Sage Chakra in his other forms.If RSM is for example partially made from the Bijuus chakra,then that could explain why he can't go into RSM,because he lost the Bijuus chakra while fighting Sasuke.
Even if he wasnt able to use RSM, he should be able to use BSM instead of KCM. Plot-wise there is no reason why he should loose RSM. Besides, if he lost it him and Sasuke would be no longer equals, which is not an option.
He did use BSM.Look at his eyes.
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it wasnt a match toneri even said u beat me with a punch. its called plot
this happens in naruto all the time
why didnt madara use preta path once he got hi rinnegan to absorb naruto's attack
how in the **** did sakura damage kaguya? theres so many stupid inconsistencies
if naruto is not even close to his former self with only KCM, sasuke would neg diff him after training with rinnegan do u really think kishi would do that with a show called NARUTO
Because he was surprised by the attack + was still recovering from the damage Gai gave him.
As for Kaguya,she was busy dealing with Naruto,and Sasuke,she was in no way paying attention to Sakura.
And yeah,it's safe to have Sasuke significantly stronger than Naruto now considering he's on the good side.
oh okay, Naruto is faster than sasuke's PS sword swing then.
She was looking right at naruto with her byakugan not activated. If sasuke was distracting her she would've had it activated.
While Naruto was worrying about Obito,Sasuke was focused on the enemy infront of him,and attacked her as soon as he could.He tried getting Naruto to join him in the battle,and told him there was nothing he could do to save Obito.
Naruto didn't listen,so Sasuke went to fight her himself.Sasuke distracted her the whole time Naruto,and Obito were talking
Reread
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If it wasn't for Sasuke's actions,she would have never been in the air above Naruto,giving him the chance to jump up,and rip her arm off like he did.Infact,if Sasuke did nothing then she probably would have attacked Obito,and Naruto.