Entry Level Trilogy: 10-18mm, 18-55mm & 55-250mm
Mid Level Trilogy: 16-35 f/4.0, 24-70 f/4.0 & 70-200 f/4.0
Holy Trinity: 16-35 f/2.8ii, 24-70 f/2.8ii & 70-200 f/2.8ii
According to the lineups above, the 16-35 f/2.8 let's the Holy Trinity down somewhat as there's many options out there that rival or best it.
My opinion and judging by how the MTF charts indicate an obvious improvement in the new wides, I see a 16-35 replacement in the form of a 12-24 before year's end.