Don't the terms of the
OGL explicitly state that any OGC can only legally be republished under the
OGL? The
GSL also explicitly states that
GSL content can't be published under more than one license. Wizards has no right to assert that a
GSL agreement into which
someone else entered somehow has the ability to invalidate an
OGL agreement into which
you entered with respect to an earlier product.
Your original
OGL agreement as it pertains to
your IP can only be invalidated by
you, not someone else. Wizards of the Coast has no such authority, nor is it granted by the
OGL.