A company absolutely cannot "revoke" CC or GPL licenses without cause, i.e. only if you do not comply with license terms and a term of the license provides for termination in the specific circumstances. The only thing they can do is choose not to release future versions under the same license terms, but only if they are the sole controller of copyright (or have agreement from all copyright holders). Oracle are a prominent example who have put great effort into their customer alienation program, by restrictively changing license terms on future versions; but they are unable to do anything about the licenses already granted for previous versions (and can't prevent people continuing to use and distribute those versions forever, other than through their obnoxious litigation policies).
There is no such thing as "GPL or CC copyright", only copyright itself. GPL and CC are licenses to use copyrighted material, and can only be initially granted by the copyright holder and their appointed agents. Someone cannot contribute code which is not their own under an alternate license; e.g. FreeBSD imports various non-BSD license code, but those portions of the project can't be published under a BSD license without permission of the copyright holders; and GPL code can't be freely used anywhere inside FreeBSD source, only as clearly separated components.
In the case of a commercially controlled open source project, the controlling company can have a "contributor agreement" in place (this is also a contract), which basically grants them the right to re-license the contributions under any terms of their choosing. There is still not any revocation of existing licenses without cause, only a potential change of license for future versions. Again, there is no conflict, as the person freely chose to contribute under specific terms and they agreed to any future re-licensing terms. If a person contributes code which is not their own in such circumstances, they are in breach of contract (both with the project they are contributing to, and the real copyright holder). Such projects can basically only accept contributions directly from the person who holds the copyright for the contribution.
Additional licenses can be offered for past versions, or terms can be relaxed (e.g. UCB's deletion of clause 3), with approval of all copyright holders, but that is the only retrospective change possible under most open source licenses.