The thing with Shirou is he's not really naive, he's just incredibly stubborn to the point where he deceives himself. Just check his thoughts right after someone criticises him on his methods, and how Shirou tends to agree.
Anyway, yes, I already agreed with the point that Shirou saw a possible future of his, and how fucked it was. My point at mentioning the fact that he let go of his past, in Fate route, was that he'd no longer follow that path out of regret.
Anyway, Shirou not ending up as Archer was said by Nasu, not by me.