I think at least some of the reported $7k-$10k price reduction for gen 2 Volt is based on using the D2XX platform. The new D2 platform will also support crossovers, so maybe we will see a Volt crossover too.
"The new compact platform will also simplify General Motors’ operations across the board, including engineering, design, sourcing, support, and tooling — giving GM the ability to enjoy increased economies of scale on a global level. And for good measure, as D2-based vehicles will be built all over the world."
"In addition, a common global architecture that supports cars and crossovers will finally allow The General to decrease time to market. At least 12 namplates will be underpinned by the D2 platform, including the next-generation versions of the Chevy Volt and Cadillac ELR."
"The Lordstown plant is expected to commence production of the all-new 2015 Cruze in the third quarter of 2014. At about the same time,
GM’s Korean operations will ramp up production for Asian markets. Platform mates are expected to follow the launch of the Cruze, and the entire D2-based model rollout is expected to be completed by 2016, according to sources."
http://gmauthority.com/blog/2012/08/gms-next-gen-d2-platform-to-support-at-least-12-nameplates/
Based on the above, it would seem that gen 2 Volt will arrive as a MY 2015 or 2016.