Sun is unlikely to release Java under an open source license if James Gosling, the father of Java, has anything to say about it.
"There's a bunch of people out there getting all hyper, and I don't believe there's anything there for them to get hyper about," Gosling said when asked about the possibility of a full open source route for Java.
Source code for Java already is available and has been for 10 years, he said. The current model for Java is close to an open source model, Gosling said. (InfoWorld)
Interesting. "Close to an open model", but not open source. Peter Yared (previously Sun's CTO of Liberty Network Identity initiative and CTO of Sun's App Server Division) and others have been publicly calling for Sun to open source Java. I tend to think that Sun should open source Java. Releasing the JVM under an open source license would have quite a few benefits (greater community innovation, better adoption within the LAMP stack, etc.)
This type of infrastructure software has become so commoditized that I do not see how Sun could possibly be getting any measurable benefit by keeping it proprietary.
Gosling also had this to say:
Despite some assertions to the contrary, Sun is doing fine with making money from Java, he said. The company earns money with its Java Enterprise System network services software and also in selling services and support, Gosling said. (InfoWorld)
Assuming this is true; Sun could continue to make money from an open source Java by offering value-added software and by selling services and support as described above.
I cannot seem to find a compelling reason for Sun to keep Java proprietary. This is especially perplexing with Sun, a company who typically "gets" open source and has done quite a bit in support of the open source community.