Face the reality KA. The E-class was conceived at a time when MB's resources were likely at their most stretched. They delivered a very conservative product that did not move the game on sufficiently. Sure it's build quality and reliability are beyond reproach now, but they have given up much ground in terms of comfort, refinement and general luxury.
Furthermore, they are simply not attracting enough younger buyers because the car is extremely conservative without the AMG sports pack. Even with it, it still looks like a product more suited to an older buyer, particularly when sat alongside the A6. As such they can't simply rest on their laurels for another 4 years for the sake of keeping happy a select few customers who only want to see evolutionary changes.
Expect to see major revisions with every facelifted benz, until they return to where they should be in terms of product competitiveness and market share. The newly released ML, A-class etc. will not be exceptions.