Let's say the miners following the rules own 70% of the total hash rate. Miners who own the other 30% are located in sanctioned countries and don't join the 70%.
What do you expect to happen? Will they stop mining? Or there will be a hard fork and they will create a separate a chain?
Assuming this scenario: They can hard fork all they want, but their fork won't be accepted in any country that enforces sanctions. So there's no point in creating the fork.