Face Down + Hidden Mana

What Kaktus suggests would be good if it's not in place already.
Would it be possible to give cards like Eikre and any other cards with a similar ability a constant ability of resetting the ? mana of the particular color, seeing as it kinda gives it away anyway? Some informationally themed cards could also then reset the ?s for a color(s) of the opponent.

btw, not tested out the new system yet, so just ignore me if I'm talking complete rubbish here...