Sigma CEO has already confirmed that they are working on new Sigma FE lenses for Sony full frame E-mount mirrorless cameras. All these new Sigma FE lenses will have new designs compared to Sigma Art series lenses.
According to recently rumors on SAR, first Sigma FE lens has been delayed until early 2018. First Sigma FE lens is likely be Sigma FE 35mm f/1.4 AF lens, and Sigma will announce all prime FE lenses that current Art lenses have. The size of Sigma FE 35mm f/1.4 AF lens is rumored be smaller than current Sony Zeiss FE 35mm f/1.4 ZA lens.