The Sigma 35mm f/1.2 has already been announced and released, but it looks like Sigma has some additional f/1.2 lenses in the works. A Sigma 50mm f/1.2 would be great, but a Sigma 40mm f/1.2 might make a more interesting option.
50mm, f/1.2 Specification and lens arrangement of embodiment 1
Focal length: 50.99 mm
F no: 1.25
2ω : 45.97
Image height: 21.63 mm
Lens length: 154.20 mm
40mm, f/1.2 Specification and lens arrangement of embodiment 4
Focal length: 41.35 mm
F no: 1.26
2ω : 57.17
Image height: 21.63 mm
Lens length: 157.00 mm
35mm, f/1.2 Specification and lens arrangement of embodiment 6
Focal length: 35.99 mm
F no: 1.26
2ω : 64.62
Image height: 21.63 mm
Lens length: 140.00 mm