>The real problem is that you would need a new hypothetical GPLv4 (since you wouldn't want to call it GPLv3 even if you could) that includes some verbiage that

>The real problem is that you would need a new hypothetical GPLv4 (since you wouldn't want to call it GPLv3 even if you could) that includes some verbiage that allows this and then get everything that is GPLv3 that you include to upgrade to this new version. GPLv3 has the same language, except with 3 instead of 2. So releasing v4 should allow both v2 and v3 programs to upgrade to v4 without anyone needing to do anything.