Dpreview had a chat with Sigma CEO Yamaki. They main topic was the Full Frame Foveons sensor development. Yamaki stated that:
Unfortunately, we have not made any significant progress since last year.
So it will still take a couple of years before (if ever) we will see a real camera using this kind of sensor. For Yamaki the upsides of this sensor (like color accuracy) are worth the effort and struggle to develop this technology.