If it were a big enough problem, could GPLv4 be published (perhaps with a clause to cover this and future laws) and products encouraged to migrate to it?
Likely not. A license can not override legislation. Like creative-commons cannot be used to give away moral rights at least if not some of the copy rights too.
But we are not talking about overriding legislation. The question is, can GPL4 say "you cannot use or distribute this software" if there is a legal risk to the creator?
A license could say that, however, the creator would still have legal risk in the case that someone broke the license. "My customer broke the license terms" is not a defense to breaking a law.
