Changing it to allow more open interpretations of each class would be interesting, imo. A Blackguard should not have to have sneak and cleave, a Shifter should not be Druid only, and it would be good to let more artistic interpretations of classes exist, rather than bound by the limiting pre-reqs. I personally, would be all for removing the pre-reqs and having it completely the DM's choice if that character could be prestigious enough to be known as a Blackguard, a Divine Champion or a Weapon Master.