I really hope they deliver on the 16-50mm f/4 IS. That would really be something interesting and new. It would make for a nice walk-around and landscape lens. I've been building a whole new lens plan based on the idea of having one.
A super sharp 16-35mm f/4 would be okay, assuming it's priced right, but still a bit of let down. The 35mm end would still be okay for a general purpose walk-around lens, but just a bit too wide to really feel like a fun general purpose lens.