It would be extremely unusual for a runner to be hit by a batted ball that the third baseman could field and that if he missed the shortstop would not have a chance at. If the ball goes past the third baseman to his left ans hits a runner there is a good chance the shortstop could have fielded it and the runner would still be out per the cited rule. About the only other way the runner could be hit would be if he was off with the pitch and was hit just as he approached 3rd base after the ball went past the pulled-in 3rdbaseman.
Runners on third never lead off in fair territory so they should never not be hit by a fair ball (except one that deflects off the third-baseman or pitcher.
I’d think a more likely occurrence would be a runner fooled by the pitcher’s move who dives back to first base as the pitch is made and he’s hit by a would be double past the first-baseman who had been holding him on.