I'd actually much prefer to have Tempered Will than another combo after Riot Blade. Awareness would be a better ability to change. I don't know if someone's figured out a use for it yet but I never use it, but haven't attempted T5 yet so who knows.

I could foresee an extension to Riot Blade's combo if GLD ever gets another job where MP is heavily used (whether it's for damage/mitigation/healing) then recovered through RB combo, or if PLD ever gets more uses for its MP besides flash in a later expansion - but for now I like the way it's working and I probably wouldn't change anything about PLD just yet.