I don't think that would happen. Most of the large tech platforms will essentially just comply or come to a deal e.g. The IPA Demand for the UK gov to have a global backdoor iCloud was only rescinded when some deal was made between the current US administration and the UK gov.

The smaller companies like 4chan are going to court to have the matter settled. If that is settled in 4chan's favour, legally the UK won't be able to do anything.

That might work if it was an instantaneous global move. Unfortunately, we're far more likely to be boiled like frogs.

Agree (as a Brit). If Wikipedia blocked the UK, it would cause an absolute storm.