The president of Sigma Mr. Kazuto Yamaki just openly said that they will make Sony FE lenses in the future! In an interview with Focus Numerique (translation here) he stated:
“The future of EF mount is beaming. So yes we will come out of FE mount objectives in the future.”
Sigma recently launched new Cine lenses with E-mount. But what Mr. Kazuto Yamaki is referring in the interview are special FE designed “normal photography” lenses.