Jesus doesn't say if you succeed you will be saved. Or if you come out on top you will be saved. He says if you endure. An accurate rendering would be, "If you hang in there until the end...if you go the distance."
The Brazilians have a great phrase for this. In Portuguese, a person who has the ability to hang in and not give up has garra. Garra means "claws." What imagery! A person with garra has claws that burrow into the side of the cliff and keep him from falling.
So do the saved. They may get close to the edge; they may even stumble and slide. But they will dig their nails into the rock of God and hang on. Jesus gives you this assurance. Hang on. He'll make sure you get home.