Make all characters more MAD, to encourage/reward more varied attribute score assignment. That will require a combination of toning down the importance of primary stats (which they have taken steps toward in recent material), creating more subclasses that use alternate stats, and just generally making secondary/tertiary stats more useful.
This is where I see it going.
Classes will get a class based mechanical benefit from 3 or more ablity scores. Classes from previous editions will be incorporated into the main classes to make them have less dependent on specific prechoice abilities. So Str wizard, Int rogues, and Cha fighters will have more advantages beside their base ability aspects.