That's possible. But if Naruto was so idealistic to that point, then Jirayia wouldn't be dead...
I see your point but I still disagree.
A story can remain idealistic even if a character dies. in 99.99% of all stories ever told, the master dies, leaving some mission incomplete. His student then completes that mission. In doing so, the student surpasses the master. Jirayia fails to defeat Pain. Naruto defeats and saves Pain, completing the mission and surpassing his master. This trope also occurs in Star Wars, one very idealistic story. Odi-wan fails to defeat Darth Vader. Luke, however, defeats and saves Vader. Luke then has surpassed his master. Star wars is very idealistic as seen the redemption of Vader and the success of very small rebellion against a HUGE empire. In sum, Jirayia's death, while tragic, is not evidence of the story not being idealistic since it opened the door for the story to be idealistic in another arc. It is the idealistic trope of the student surpassing the master.
For something to be considered cynical, the heroes have to be repeatedly defeated and almost never triumph. For an example, see Game of Thrones. Just when you think the heroes (or the slightly less bad villains) maybe might have a chance of winning, the villains win. That is a cynical show. However, with this, the heroes win virtually ever single arc. Off the top of my head, the heroes only lose in three or four arcs. That's a pretty good track record.
More evidence to Naruto's idealism can be seen in Jirayia's teachings. Jirayia honestly believes that Naruto can bring about world peace. He is not mocked for this as he would be in the real world. He and others believe this to be possible. that's very idealistic. I mean, for goodness sake, according to Naruto, having child soldiers does not have consequences on the child's mind. That's about as idealistic as you can get.
Also, most stories have dark points in the middle, such as Jirayia's death. Even the Hobbit (I take back what I said previously. The Hobbit is the most idealistic thing I've ever read) had the dark journey in the Forest of Mirkwood. However, the hobbit is still idealistic. In sum, you cannot say because this happened in the middle, then this story is not idealistic.
I think Sasuke will restore his clan and overcome the curse of hatred. If this does not happen (an event that I hold to be unlikely), then at the very least Sasuke will do what Zabuza did and die a hero.
edit: Moreover, Pain was much more evil than Sasuke, as evidenced in this destruction of the village (Sasuke came to his senses before that happened) and killed his Jiriyai and Kakashi. Then he got redemption. If Pain got redemption, but Sasuke does not. That would just be inconsistent writing in my opinion.
