Totally unsubstantiated speculation:
In the new AAdvantage materials, it looks like there are four colors for AAdvantage cards. Perhaps the black card is the new CK card and they will roll out this higher formal level.
I can't see them continue to push the "focus on premium passengers" angle without doing more with CK.
As an EXP that would probably never reach CK, I wouldn't mind this as long as EXP retains its current benefits and is mileage based. My company is too cost conscious domestically to qualify on spend.