If Sasuke assumption is correct, than their is no way that Naruto lost his Rikudo sage mode, because according to Sasuke their is someone stronger than Kaguya. They need to team up again to deal with the new enemy.
Of course he still has it, he gain the ability to go into the mode from Hagoromo yang chakra but if he lost it then that means Sasuke lost Hagoromo yin chakra which means he lost the Rinnegan which requires Hagoromo chakra to awaken. Since we clearly saw Sasuke using the Rinnegan in the last, 2 years after war arc, it's safe to say they both have their powerups.
Naruto is stronger than he use to be so he didn't need to use RSM.
No, Naurto has 100% all bijuus now, he is stronger than rsm
No he doesn't, he has full Kurama but has only a small amount of the other Bijuus chakra; for Naruto to have 100% of all Bijuus chakra means Bee wouldn't have the 8 tails who we see with Bee in ch. 700. Naruto's current BSM (full Kurama) is on War arc RSM (Yin Kurama) level or stronger which put current RSM (Full Kurama) on another level. Full Kurama chakra reserve is twice as big and is much more powerful than Yin or Yang Kurama which only increase and becomes more powerful when combined with Senjutsu.