I propose to switch from "GPLv2-only, GPLv3-only, Proprietary" to "GPLv2+, Proprietary" licensing model.
I understand your potential concerns with uncertainty of such an approach.
However, despite already being possible, it simplifies integration with projects which are under GPLv2+
It might seem unnecessary due to a lack of such projects using V-USB, but it is only because V-USB does not allow for that yet.
An example scenario showing why it is needed:
GPL v4.0 (v3.5) is released
V-USB project updates to support GPLv4 with ease due to the centralized copyright maintained for the Proprietary licensing option.
Projects utilizing V-USB are struggling, or just not bothering with the change, as it involves getting permission from every contributor, making them stuck with the outdated GPL options, making it impossible to make use of this code in opensource projects under the new GPL.
Project borrowing code from the above projects are also subject to the above, as they cannot be licensed under GPLv2+.
This change would open up V-USB code to the vast number of projects using GPLv2+ and GPLv3+ licenses.
(Sorry for multiple edits - posted this before I finished typing)
I propose to switch from "GPLv2-only, GPLv3-only, Proprietary" to "GPLv2+, Proprietary" licensing model. I understand your potential concerns with uncertainty of such an approach.
However, despite already being possible, it simplifies integration with projects which are under GPLv2+ It might seem unnecessary due to a lack of such projects using V-USB, but it is only because V-USB does not allow for that yet.
An example scenario showing why it is needed:
This change would open up V-USB code to the vast number of projects using GPLv2+ and GPLv3+ licenses. (Sorry for multiple edits - posted this before I finished typing)