I'd prefer it if they kept the fist elements but had them relate to Chakra and be temporary buffs, like riddles. Give them the WAR Berserk treatment so to speak.

Fists of Fire could give the standard DPS boost, eventually upgrading into Riddle of Fire which could give some Chakra when used, too.

Fists of Earth could function exactly as Riddle of Earth and eventually upgrade into it with charges and directional ignoring added. Maybe grant 1 Chakra if damage is taken while RoE is up.

Fists of Wind could increase movement speed for a short period and upgrade into Riddle of Wind which could give Chakra a temporary overflow for high generation phases.

Then, with these abilities giving chakra, we could add in more abilities that use the resource. Perhaps abilities that are altered by previously used Fists/Riddles - kind of like how the stances altered Shoulder Tackle in SB (but not exactly like that again).