It's the thread that never ends.
Sarah: Well, we can change it Kyle. We have to at least try. There's no fate but what we make for ourselves. We have to at least try. What do you say, kiddo?
For those who don't know, I'm a professional actor. We have a saying in the theatre. 'If it's not on the page, it's not on the stage'.
I must still conclude that the future is mutable or that multiple timelines are possible in T1 alone.
The movie is also careful to point out Reese doesn't understand time travel and he's just repeating what he was told.
The lines are really just exposition for the audience to create the illusion of danger and set up the twist ending.