GPL-v3 and closed source license

Say there is an existing plugin open source GPL-3.0-only, and we (including the copyright holder) want to expand to include other modules where it is potentially not possible to open source, what are my options? The plugin would remain free either way, and the GPLv3 source to potentially be included in the closed source project won’t be modified.

My initial feeling is that this wouldn’t be possible, however it appears the copyright holder can relicense if they like (of course once GPLv3’d, the pre-existing version of the code has to remain available with that gpl license).

option 1: Feels like the simplest thing is to release a seperate closed source plugin but with the same brand. option 2: If it’s possible/legal to consolidate into a single closed source plugin then that is less confusing for users. In the latter scenario, the copyright holder relicenses to be compatible with free but closed source, and the updated plugin is distributed on VCV as closed source freeware.

Any advice welcome, thanks!

If all contributors to that GPLv3 project agree than they can re-license however they want, but if you have contributors that do not, then you cannot do this.

(This is the reason that VCV doesn’t allow contributions to Rack2, so that they can re-use the code in the closed Rack2 Pro)

Understood, I’ll need to confirm this.