What I would like to see in future monk!

[Shurrikhan]

Something like the same button will execute Fire Dance if you're in fists of fire, but would do Razor Gale if you're in firsts of wind.

Atop that concept and ones similar to it, if we get rid of Greased Lightning as such, we could perhaps switch over to a granular resource (call it, say, "Ki") or the like which could then be consumed by the different stances, allowing the stances to be used as shared resource burst phases to be rotated between in a flexible manner. For instance, have this "Ki" resource be generated by relative potency dealt or absorbed. Using Fists of Wind gives additional means of spending Ki (e.g. Shoulder Tackle becomes Wind Spike, with a reduced cooldown which could be further "rushed" at Ki cost) atop a variable drain rate and passive benefits (e.g. Ki spent within the stance thus far steadily increases its drain rate and added Attack and Movement Speed). Want uber-speed immediately? Spam Wind Spike. But, your Fists of Wind phase will last that much less time. Or, we could just have Wind Spike offer added Attack and Movement Speed with each use, with each Wind Spike's consequent bonus fading individually, for even more control but less sense of a deliberate "Wind" phase.

Of course, we'd also want to decide if stances ought to be able to be cancelled by swapping to another stance only, also by cancelling the stance, or only upon either Ki depletion or after one fails to sustain the stance through some relevant action. To give an example of that last option, we could have it so Fists of Wind automatically ends if you don't Wind Spike within X seconds, based on drain rate, so that you have the option to drop out of Fists of Wind early without what might seem like the bloated or mundane option of just turning the stance off.

You could then keep "Riddle of X" on its 90-second cooldown, but able to interact with any of the above stances, either staying as the first stance used during the effect (or active when Riddle was triggered) even as one swaps to something else (if we go that route), or swaps its bonus with any later swaps.