To accomplish what?

The root of the "problem" is that *A does not have a consistent product. Some member airlines offer First Class, others don't. Some have Premium Economy, others don't. Some have two levels of lounges, others don't. Some offer complimentary food and/or alcohol on-board, others don't. Some extend additional (beyond the *A minimum) benefits (access to upper level lounges, preferred seating, priority security...) to other member airlines' elite members, others don't, etc... Given this, what exactly would be fixed by introducing a third tier? Perhaps they should start by cleaning up what they've already got?