Sigma will be announcing a few lenses for Photokina in the coming weeks.
The first will be the expected Sigma 24mm f/1.4 Art, which will be priced around $1100. The second will be a 14-24 f/4 DG OS that will be priced around $1200. The 14-24 will have an 82mm filter thread, which will be a very welcomed feature for landscape photographers.
There's also a mention that Sigma could make a development announcement for a 24-70 f/2 that we spoke about a year or so ago.