Thing is this lens must happen and performance must not be compromised.
I believe that if this lens delivers unparalleled performance, filters will happen.
I started my photographic journey three years back and from the reviews, the user feedback I read, there were three lenses that were considered necessary but were not loved. Canon 50mm f/1.4, 24-70 f/2.8 mki and the 16-35mm f/2.8 mkii.
Hopefully the 50mm f/1.4 will have a story that unfurls like the 24-70's did. The Canon EF 24-70mm f/2.8 mkii has changed sentiment across the photographic community. From comments like 'necessary workhorse' to 'I don't like the 24-70 but I need it for my work', the mkii has people raving! It's as good as the 70-200 f/2.8 mkii and has become as desired.
Canon need to acknowledge that the 16-35 f/2.8ii needs similar treatment. They need to keep in the back of their minds that professional togs who spend big money on equipment sometimes buy Tamron or Sigma UWA because their flagship lens underperforms.
I for one am extremely hopeful, judging by the new 16-35 f/4.0, I believe that Canon has a recipe for success. I've got my fingers crossed.