GM is considering allowing other automakers to use the Volt powertrain. Dan Nicholson, GM VP of Global Powertrains, confirmed this in an interview with Automotive news saying, "We have a history of being a good partner" and "We want to be the partner of choice in propulsion system development in this complex and turbulent era we are approaching."
Nicholson did not say that any companies have approached GM about this, but the move could be beneficial to both GM and its rivals. Rivals would gain access to the Voltec powertrain (FCA maybe?), and GM would be able to recoup development costs from the research and development spent on the engine.