Sigma CEO Kazuto Yamaki confirmed on Twitter that upcoming Sigma lenses will mostly be DN series full frame & APC-S lenses for mirrorless cameras. This means Sigma will make more full frame lenses for L-mount mirrorless cameras.
From Sigma CEO: (Translated by Google)
Most new products in the future will be the DN series designed exclusively for mirrorless cameras. The DG DN series for full-size mirrorless, which is frequently requested, will be the center, but we believe that we need to expand the DC DN for APS-C (+ MFT), which is currently popular.