Depends on who wants to take what away.

If I release blub 1.0.0 under GPL, you cannot fork it and add features and release that closed-source, but I can certainly do that as I have ownership. I can't stop others continuing to use 1.0.0 and develop it further under the GPL, but what happens to my own 1.1.0 onwards is up to me. I can even sell the rights to use it closed-source.