[boomboomsubban]

>which will automatically apply to software licensed under the GPLv2 or GPLv3 with the "or any later version" clause (which is present in the standard boilerplate).

Unless I'm missing something, the "or any later" clause means that a new GPL would cause further software releases to be dual licensed as GPL v2/3 and 4. The project could choose to go to v4 only, or continue releasing it under both.

I can only imagine that causing problems if they say released a non copyleft v4, and it's hard to see that surviving a legal challenge.

[Denvercoder9]

> Unless I'm missing something, the "or any later" clause means that a new GPL would cause further software releases to be dual licensed as GPL v2/3 and 4.

It also causes past releases to be immediately and retroactively available under the GPL v4 (in addition to the GPL v2/v3 it was already available under). As such the FSF has the power to make a large amount of software available under a new license.

> I can only imagine that causing problems if they say released a non copyleft v4, and it's hard to see that surviving a legal challenge.

A hypothetical GPLv4 has to be similar in spirit to the previous GPL licenses, but the devil's in the details -- just look at the prolonged debates about GPLv3. Depending on the exact details it might not be acceptable to parts of the free software community.

[boomboomsubban]

> hypothetical GPLv4 has to be similar in spirit to the previous GPL licenses,

This doesn't cause an issue though, the software is still licensed under v3. A more restrictive v4 can be ignored, an issue would only arrise from a less restrictive v4.