We know that Canon doesn't really support or motivate third parties to build RF mount…
SIGMA 105mm F/1.4 DG HSM ART development announcement
Release date and price of the Sigma 105mm f/1.4 are not known yet.
Sigma press release:
Development announcement of SIGMA 105mm F/1.4 DG HSM | Art
The SIGMA Corporation is pleased to announce the development of the SIGMA 105mm F/1.4 DG HSM | Art, the longest focal length of the F1.4 Art series.
Since introducing its first SIGMA Global Vision F/1.4 lens in 2012, the 35mm F1.4 DG HSM | Art, SIGMA has been adding wide-aperture F1.4 options to the lineup. Now, with the introduction of the new 105mm F/1.4 DG HSM | Art, SIGMA offers a total of nine lenses with F1.4 brightness, including six for full-frame cameras and three for APS-C cameras. SIGMA has designed all of these lenses to offer minimal optical aberration and deliver incredible resolution and stunning contrast. Boasting the longest focal length of the F1.4 Art line lenses, the new lens combines outstanding resolution with a beautiful bokeh effect. Designed with great care to ensure that both the in-focus and out-of-focus areas of the photograph are equally satisfying to the eye, this lens is truly a “bokeh master.” The SIGMA 105mm F1.4 DG HSM | Art has earned its place as the flagship of the F1.4 Art line lenses, prioritizing image quality above all to fulfill the promise of the line, delivering truly amazing optical performance.