Original link: Free Software Foundation rides to defend AGPLv3 against Neo4j license add-ons / TheRegister.
As a non-lawyer I think the deciding factor will be if all copyright holder has agreed to relicensing. Yes => valid action, nobody prevents ccopyrights holders from making their work available under multiple licenses of their choice. No => that copyright holders code is still under AGPL => all code must be available udner AGPL => not a valid action.