They should remove all padding and safety equipment, and institute severe penalties for any contact that could cause injury. The sport would probably become sane, but people like the violence, so this isn't going to happen.

~60% of rugby league players in one study were found to have CTE [0]. I bring this up because they don't wear pads, and I often hear (ETA: and even saw another commenter here post) that this makes them play safer (which might be true, but not to a meaningful degree; they still are not "safe").

FWIW, the NFL seemingly increasingly penalizes and expands the definition of unsafe hits every year. If people just liked the violence, BKB or power slap would be much more popular than they are.

0 - https://apnews.com/article/cte-australia-rugby-league-035e24...