New zoom lens from SIGMA

Sigma 24-35mm f/2 Art Lens for FX announced:
SIGMA 24-35mm F2 DG HSM ART Lens for Fullframe Camera Announced « NEW CAMERA
I've been thinking of buying Sigma 35mm f/1.4 to cover the middle range in addition to my Nikon 50mm f/1.8, which is the only lens I currently have for the range 35-70mm. Now if this lens performs 99% of the prime and the cost is similar then I'd buy it.

Second thought: Since I already have 16-35mm f/4, which is much lighter even though not as fast, instead of buying this lens I should buy Fuji X-T10 + 18-55m f/2.8-4 as a walk-around camera+lens combo ???