WIPO requires signatory countries have some sort of legal protections to back copy protection, but it does not mandate the exact language of DMCA 1201. The WIPO requirement was actually added by the US after the EFF managed to kill a precursor bill a few years prior[0].
Implementation among signatory countries is high enough to laugh when people say "Well, this doesn't affect me because I'm not American." Unless you live in North Korea or Russia, DMCA 1201 applies to you.
Copyright law is so foundational to world trade that the only way 1201 would get repealed would be if there was some kind of mass uprising against copyright overreach in many signatory countries. In that case, so many large countries would have repealed their DMCA 1201 equivalent legislation that nobody would dare actually try to enforce WTO sanctions against them. At worst, a few countries would demand some horse trades[1].
Practically speaking, however, democracies are bad at protecting against small harms exacted against large numbers of people[2], so this never happens. Europe has the Pirate Party but the most successful national iterations of it have had to adopt broader Green[3] and technolibertarian agendas in order to have any semblance of electoral viability. In the US, first-past-the-post is an insurmountable hurdle despite the fragility and incompetence of our two major parties. Here, political issues don't so much form new parties as much as they infect the shambling corpses of existing ones.
Barring that, if only one country decided to repeal their anti-circumvention laws I imagine there'd be a lot of grumbling from the US or Japan, potentially new tariffs, but no outright sanctions. The weird part about world trade is that a lot of these provisions are only enforceable on very poor countries. China blatantly violates WIPO all the time and we, practically speaking, cannot quit them. There is no international leviathan capable of, say, rolling tanks on Beijing and demanding market access and copyright enforcement.
[0] https://en.wikipedia.org/wiki/Policy_laundering
[1] Term of art for "unrelated and usually minuscule things used to bargain for a larger purpose"
[2] e.g. how Intuit got the US government to not provide tax preparation services or software to the public for a decade and a half so they could sell their own offering. It's a thing that annoys people but not enough to get voters to flip sides.
[3] including German "Green", i.e. "nuclear is bad, so we shut down all our nuke plants and started burning lignite[4] instead"
[4] What's lignite? Lignite balls.