Converting/Splitting Code - Open to Closed

[Ralph Bloemers]

A colleague just asked me the following question, any thoughts from the list?

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Can the OWNER of the copyright in software code that has been released under a GPL 
(http://www.gnu.org/copyleft/gpl.html) change its mind and take the software *private* 
(any future versions would be proprietary and released only under typical object code 
only licenses)?

In reality, the code would most likely *fork,* leaving one strand open and the other 
proprietary.

Oh, and, at least for now, I'm not concerned about enforceability or who would have 
standing to sue.
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Thanks,
Ralph