@aral >I don’t necessarily trust what will come next from the FSF given how they’ve handled stuff recently.
I don't have many complaints about how the FSF handled stuff recently.

The upgrade clause is very carefully designed; "The Free Software Foundation may publish revised and/or new versions of the GNU General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns."

As a result, if say the GPLv4 was a proprietary license, such new version wouldn't be "similar in spirit", so thus would be legally invalid.

You don't need to worry about later versions being the slightest bit proprietary, as there are numerous free software extremists like me that will never allow that to happen.

>I already use the latest versions of the licenses in my work and I plan to review any new versions that come out, if they do, and update my licenses accordingly.
That may work out if you're the latest copyright holder and you don't get into a situation where you can't upgrade to the latest version for years, but as soon as there is multiple contributors, big problems start to happen.

It may be a good idea to use the proxy option if you have misplaced doubts; "If the Program specifies that a proxy can decide which future versions of the GNU General Public License can be used, that proxy’s public statement of acceptance of a version permanently authorizes you to choose that version for the Program."