Many countries already do this.
Some have gone to their tier 1 ip transit and they intercept at the border.
Some have gone to their isps and told them to do it to their end users. Like 'block these piracy websites, and here's a legally forced nda and you're also blocking X, Y, Z.'
When duckduckgo publicly admitted they will be blocking russia... they proved to everyone they had the ability to block.
When duckduckgo decided to start blocking piracy. But when caught they reversed course. Incidentally torrentfreak noted the piracy websites returned at exactly the same time the CEO tweeted blaming someone else.
Duckduckgo basically proved to everyone they are censoring, eliminating their entire value.
