I can imagine them doing a bard-ish thing for the fists.
Like, Fists of Fire increase your crit rate for the next 20s, earth makes it so that you charge a chakra when doing a positional correctly during the next 20s, wind increase your skill speed and run speed for 20s.
Not sure it would work well, but I can see them going that way, and push further into the proc-based design of chakra, and making MNK the proc-based melee.