Reporting from Toy Fair 2013, figure and toy site TOMOPOP got a nice look at Bandai's next entry in the Mega Man D-Arts line: Bass. You can check out their report for more photos and details.
Furthermore, the reporter was also able to bring up the current status on other D-Arts toys, and got some interesting feedback about Sigma. He reports: "Also, you may be wondering what happened to D-Arts Sigma. He wasn't forgotten about, but there is some trouble in engineering land as the joints pose a problem given his size. He's not forgotten, but expect him to be released as a D-Arts Zero."
I'm not sure exactly what "as a D-Arts Zero" means, but I'm thinking it means Sigma will be of a more comparable size to a figure like Zero. Nevertheless, we've reached out to Bluefin for further details. Check back soon!