Naruto and Sasuke are to take the places of Ashura and Indra as the Reincarnates. There was Naruto 697 never anything about that cycle ending or how to stop it completely. Yang Kurama has been freed. If it was a normal Rasenshuriken, then sure. But this is a Rasenshuriken enhanced by using Senjutsu and Tailed Beast Chakra. That alone seems like it should equal or overpower Sasuke’s Lightning Arrow.
But the Tailed Beast Ball Rasenshuriken is what I’m talking about. A human sized one was capable of doing this. The one Naruto has in his hand is way bigger than that one. It just seems unlikely that a single Lightning Arrow could handle something with a elemental advantage and a possible destruction output. But I’m sure positive that the arrow is extremely powerful being made from Tailed Beast Chakra. We’ll just have to wait for the outcome.
We were made to think that Naruto would be an outsider, someone who was not tied into the chain of the past. Then we found out this nigga is from the Uzumaki Clan, who were distant relatives to the Senju, who were in fact descendants of the Sage’s son, who was in fact the children of the Sage himself. Then he gets thrown into the mix of being Ashura’s reincarnation. It would’ve been a lot better if Naruto was not tied into these clan-orgies because then he would’ve been a normal kid fighting for a cause through sheer determination that did not involve him genetically. More so, it would’ve made Naruto’s choice to continue this campaign, all the more worth it.
I wouldn’t say it is necessary to tell viewers that the show had reincarnations in it, although I do believe you are missing the main component of his statement. By tying Naruto into this reincarnation web, his individualism and independence in changing the world, seems more of something that was predestined, more than it was Naruto’s own personal choice to change his and the destiny of the shinobi world. If you re-watch or re-read this entire manga, you would realize how Kishi tries to keep Naruto’s consistency of choice, but fails to do so when he started linking Naruto to this web-chain.
Note: Now reading the entirety of your second paragraph, you missed what Rendarg truly meant. And just so you know, a manga author DOES reveal everything, but in certain increments/timing. It’s all about how and when it is delivered, remember that please.