If 4chan continues to ignore Ofcom, the forum could be blocked in the UK. And 4chan could face even bigger fines totaling about $23 million or 10 percent of 4chan’s worldwide turnover, whichever is higher. 4chan also faces potential arrest and/or “imprisonment for a term of up to two years,” the lawsuit said.
They could go after the owner. I believe he lives in Japan, all the UK has to do is send an extradition request to the Japanese government, bing bang boom all done.