Dissension
Member
Granted Naruto does know about the pain, the death of a loved one brings. But there is more to it than just that. The setting, how, why, etc... all play a toll, and make the death of the individual different.He already knows the "pain", Jiraiya is the key example. I really don't think Sakura will die(although I wouldn't be sad if she didxd) but it would be interesting for her to get close to death. Then Rock Lee will come to her rescue and they will fall in love(lollll).
The 3rd, 4th, Kushina, Jiraiya, all died sacrificing themselves for the future of those they loved most.
Sakura dying, saving lives, would have a totally different affect on him I believe.