Just some random thoughts I've had about it.

Greased Lightning would be removed. The speed would instead be moved to Wind stance and the damage to fire stance.
The normal form rotation stays, but where before we would get a GL stack, it would now fill a gauge.
The gauge can then be spent on a phase opener similar to the PLD magic opener oGCD. The phase opener will further boost damage and crit. Time on the phase depends on the amount of gauge spendt(with a minimum needed to activate)
The phase will open a new combo string similar to how GNB works. Axe Kick followed by Somersault and finishing with Six Sided Star. Having full gauge will allow for this rotation twice. To act as a phase closer will be Tornado Kick with potency depending on how much gauge was used.
Potencies and own buff durations would need to be adjusted.
A crit would always give a chakra stack instead of the current 70% chance.

The idea would be a flow of building gauge in wind stance, switch to fire stance and use the gauge for a burst phase, then switch back to wind to rebuild.
Anatman would be switched to build gauge similar to samurai's meditate.