So, why in TESB Luke's sister is Yoda and Ben's last hope ? With that idea that "everyone can be a jedi" would just make Luke and his sister less important characters that could have easily been replaced by other "force believers". Why Vader even wants to "train" Luke as his apprentice when he can just train another person instead ? That's because Luke has far more potential than other people of the galaxy due to his bloodline. Force sensitivity has always been related to the bloodline since the release of episode 5.