IIRC the OGL license is unrecallable, unlike the newer GSL. OGL can't be canceled and whatever is released as Open Content remains Open Content forever; GSL (which is the license for 4E) can be modified, recalled or canceled by WotC.EDIT: HERE
is a relevant thread from ENWorld.EDIT #2: HERE
is the relevant page on Wizards' site. The important part is:
Q: Can't Wizards of the Coast change the License in a way that I wouldn't like?
A: Yes, it could. However, the License already defines what will happen to content that has been previously distributed using an earlier version, in Section 9. As a result, even if Wizards made a change you disagreed with, you could continue to use an earlier, acceptable version at your option. In other words, there's no reason for Wizards to ever make a change that the community of people using the Open Gaming License would object to, because the community would just ignore the change anyway.
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