And I don’t think that making Whites, Magics and Rares obsolete is the right path.
Try to think of it this way:
The color of an item merely indicates how many and what kind of stats you can expect to find on an item.
The “power level” is solely determined by how well those stats fit into your character build.
Every single Diablo Game so far had completely useless Uniques/Legendaries and this will most probably not change with D4, so item tiers have never been a reliable power indicator to begin with.